Earthquake detection system and method

Abstract

1. A method for detecting earthquake events, the method comprising the steps of: a) collecting acceleration data over a given period of time from one or more accelerometers located on a grid framework structure, the grid framework structure comprising: i) a first set of horizontal grid members extending in a first direction; ii) a second set of horizontal grid members extending in a second direction substantially perpendicular to the first direction and intersecting the first set of horizontal grid members at an intersection; the first set of horizontal grid members and the second set of horizontal grid members arranged in a horizontal plane to form a grid comprising a plurality of substantially rectangular frames, the plurality of substantially rectangular frames being spaced apart from one another; iii) a plurality of upright columns supporting a first set of horizontal grid members and a second set of horizontal grid members, the plurality of upright columns forming a plurality of vertical storage locations for containers to be stacked between the upright columns; b) comparing the collected acceleration data with ground acceleration data from one or more accelerometers located on the ground; c) determining a differential acceleration between the acceleration data and the ground acceleration data; d) determining displacement data from the differential acceleration; and e) determining whether a seismic event has occurred over a given period of time based on the displacement data.

Description

[Technical field]

[0001] The present invention relates to the field of seismic detection systems and methods for a grid framework structure that supports a remotely operated load handling device on a truck located on the grid framework structure for handling storage containers or bins stacked in the grid framework structure. [Background technology]

[0002] Storage systems comprising a three-dimensional storage grid structure in which storage containers / bins are stacked on top of one another are well known. PCT Publication No. WO2015 / 185628A (Ocado) describes a known storage and fulfilment system in which a stack of bins or containers are arranged within a grid framework structure. The bins or containers are accessed by remotely operable load handling devices on trucks located on top of the grid framework structure. A system of this type is shown diagrammatically in Figures 1 to 3 of the accompanying drawings.

[0003] As shown in Figures 1 and 2, stackable containers, known as bins or containers 10, are stacked on top of one another to form a stack 12. The stacks 12 are arranged in a grid framework structure 14 in a warehousing or manufacturing environment. The grid framework structure consists of a number of storage columns or grid columns. Each grid in the grid framework structure has at least one grid column for storage of a stack of containers. Figure 1 is a schematic perspective view of the grid framework structure 14, and Figure 2 is a top-down view showing a stack 12 of bins 10 arranged within the grid framework structure 14. Each bin 10 typically holds a number of product items (not shown), which may be of the same or different product types, depending on the application.

[0004] The grid framework structure 14 comprises a plurality of upright members or columns 16 that support horizontal members 18, 20. A first set of parallel horizontal grid members 18 are disposed at right angles to a second set of parallel horizontal grid members 20 to form a plurality of horizontal grid structures supported by the upright members 16. The members 16, 18, 20 are typically fabricated from metal and are typically welded or bolted together, or a combination of both. The bins 10 are stacked between the members 16, 18, 20 of the grid framework structure 14 such that the grid framework structure 14 guards against horizontal movement of the stack 12 of bins 10 and guides vertical movement of the bins 10.

[0005] The top level of the grid framework structure 14 includes rails 22 arranged in a grid pattern across the top of the stacks 12. With further reference to FIG. 3 , the rails 22 support a plurality of load handling devices 30. A first set 22a of parallel rails 22 guides movement of the robotic load handling devices 30 in a first direction (e.g., X direction) across the top of the grid framework structure 14, and a second set 22b of parallel rails 22, arranged perpendicular to the first set 22a, guides movement of the load handling devices 30 in a second direction (e.g., Y direction) perpendicular to the first direction. In this manner, the rails 22 enable movement of the robotic load handling devices 30 laterally in two dimensions in the horizontal XY plane such that the load handling devices 30 may be moved to a position above any of the stacks 12.

[0006] A known load handling device 30 shown in Figures 4 and 5 is described in PCT Patent Publication No. WO2015 / 019055 (Ocado), incorporated herein by reference, comprising a vehicle body 32, with each load handling device 30 covering only one grid space of a grid framework structure 14. Here, the load handling device 30 comprises a wheel assembly comprising a first set of wheels 34 consisting of a pair of wheels on the front of the vehicle body 32 and a pair of wheels 34 on the rear of the vehicle body 32 for engaging with a first set of rails or tracks to guide movement of the device in a first direction, and a second set of wheels 36 consisting of a pair of wheels 36 on each side of the vehicle body 32 for engaging with a second set of rails or tracks to guide movement of the device in a second direction. Each of the sets of wheels is driven to enable movement of the vehicle in the X and Y directions respectively along the rails. One or both sets of wheels can be moved vertically to lift each set of wheels off of its respective rail, thereby allowing the vehicle to move in a desired direction.

[0007] The load handling device 30 is equipped with a lifting device or crane mechanism for lifting the storage container from above. The crane mechanism comprises a winch tether or cable 38 wound on a spool or reel (not shown) and a grabber device 39. The lifting device comprises a set of lifting tethers 38 (one tether near each of the four corners of the grabber device) that extend vertically and are connected near or at the four corners of a lifting frame 39, sometimes known as the grabber device, for releasable connection to the storage container 10. The grabber device 39 is configured to releasably grip the top of the storage container 10 to lift it from a stack of containers in a storage system of the type shown in Figures 1 and 2.

[0008] The wheels 34, 36 are positioned around the periphery of a cavity or recess in the lower portion known as the container receiving recess or space 40. The recess is sized to accommodate the container 10 when it is lifted by the crane mechanism, as shown in Figures 5(a and b). When in the recess, the container is lifted off the lower rail to allow the vehicle to move laterally to a different location. Upon reaching the target location, e.g., another stack, an access point in a storage system or a conveyor belt, the bin or container can be lowered from the container receiving portion and released from the grabber device.

[0009] In other examples, the container receiving space 40 of the load handling device 30 may not be located within the body 32 of the load handling device 30. For example, in some examples, the container receiving space 40 may be adjacent to the body 32 of the load handling device 30, e.g., in a cantilever arrangement where the weight of the body 32 of the load handling device 30 balances the weight of the container to be lifted. In such embodiments, a frame or arm of the lifting device may project horizontally from the body 32 of the load handling device 30, and the lifting tethers 38 may be positioned at respective locations on the projecting frame / arms and configured to be raised and lowered from those locations to lift and lower the container 10 into the container receiving space 40 adjacent to the body 32.

[0010] The grid framework structure is subjected to various external and internal forces, including but not limited to ground movement which may be due to the composition of the ground or soil type, forces caused by movement of load handling devices on the grid framework structure which may weigh more than 100 kg, movement as a result of nearby structures or moving vehicles such as trains, and even during earthquakes or storms. It is of utmost importance that the individual elements within the grid framework structure remain intact as a result of such external forces experienced by the grid framework structure.

[0011] To ensure the stability of the grid framework structure, prior art storage systems rely heavily on various supports and bracings located within or at least partially along the perimeter of the grid. However, the use of various supports and bracings (anti-shift braces) to stabilize the grid framework structure from internal and external forces is disadvantageous for several reasons. The grid framework structure occupies space or area that could be utilized by the grid to store containers, thus preventing optimal use of the available space or area for the storage of containers. The need for support structures may limit the available options for the positioning of the grid framework structure, as any auxiliary grid support structure often requires a connection to the surrounding structure, such as the interior walls of a building, and the requirement of a support structure that is not cost-effective.

[0012] WO2019 / 101367 (Autostore Technology AS) teaches a grid support structure for integration in a storage grid structure of an automated storage system. The grid support structure consists of four storage columns interconnected by a plurality of vertically inclined support struts. The storage column profile has a cross section with a hollow central section and four corner sections, each corner section with two right angle bin guide plates for accommodating the corners of a storage bin. The support struts have a width that allows them to fit halfway between two parallel guide plates so as not to impair the storage column's ability to accommodate a stack of containers or storage bins.

[0013] There is therefore a need for an alternative grid framework structure that minimizes the impact on the available space or area for storage of containers to provide a free-standing storage grid, or at least requires less extensive auxiliary grid support structures.

[0014] A large portion of the world's population is located along earthquake fault lines or in the path of powerful storms, such as hurricanes and tornadoes. Locating grid frame structures in such areas is at risk of structural damage from earthquakes and storm events, as current grid framework structures may not hold the grid structure together. Powerful earthquakes and storm events may result in failure of their structural integrity, for example, as a result of the structural fasteners being unable to keep the grid rigidly attached to the upright members. Earthquakes may be labeled into four categories, labeled as Type A, B, C, or D, depending on the severity of the earthquake, with Type A being considered the least powerful earthquake and Type D being considered the most powerful earthquake. Types A-D may be graded by their spectral acceleration, which is the maximum acceleration measured in g that an object above ground level would experience during an earthquake. Type D, considered to represent the most powerful seismic events, generally has measured spectral accelerations (Short-term Spectral Response Accelerations SDS, see https: / / www.fegstructural.com / seismic-design-category-101 / ) in the range of 0.5g to 1.83g and results in the failure of most of the building. When a powerful seismic event acts on a structure, the three-dimensional dynamic forces can compromise the structural fasteners that hold the grid framework structure together, causing the structural fasteners to gradually loosen or come out of the members in which they are embedded, or, if the structural fasteners remain in place, they can break through the structural fasteners.

[0015] Many jurisdictions, such as states in the United States, have passed laws mandating that all new buildings, residential or commercial, be built with some earthquake bracing feature built into them. A grid framework structure is shown in FIG. 6 with an internal bracing feature built into the grid framework structure whereby one or more of the upright members are braced together by one or more bracing members or bracing towers. Generally, the bracing members are distributed internally throughout the grid framework structure. The distribution of the internal bracing is highly dependent on the size of the grid framework structure, ground conditions, and environmental conditions such as temperature. However, while grid framework structures are capable of withstanding extremely low level earthquake events having spectral accelerations less than 0.3g, there is currently no earthquake suppression system for grid framework structures that is capable of withstanding stronger Type C and Type C earthquake events, categorized by spectral accelerations in the range of 0.5g to 1.83g.

[0016] Following a seismic event, the condition of the grid framework structure needs to be assessed. While manual inspection following a seismic event is possible, it is of course preferable to understand the condition of the grid framework structure before bringing in personnel.

[0017] The first step before damage in a grid framework structure can be remedied is to understand the extent of the damage, particularly to measure the extent of yielding in the grid framework structure. Doing this manually would require measuring the positions of structural members at the edges and inside the grid framework structure, which is a labor-intensive and time-consuming process. Another method of measuring displacement that does not require manual intervention is needed.

[0018] Therefore, there is a need for an earthquake detection system that can determine whether a seismic event has occurred and assess the degree of deflection of a grid framework structure without the need for a human to enter the grid and take manual measurements. Summary of the Invention

[0019] One aspect of the present invention is a method for detecting an earthquake event, the method comprising: a) collecting acceleration data over a given period of time from one or more accelerometers located on a grid framework structure, said grid framework structure comprising: i) a first set of horizontal grid members extending in a first direction; ii) a second set of horizontal grid members extending in a second direction substantially perpendicular to the first direction and intersecting the first set of horizontal grid members at an intersection, the first set of horizontal grid members and the second set of horizontal grid members being arranged to form a grid comprising a plurality of substantially rectangular frames in a horizontal plane, each of the substantially rectangular frames defining a grid cell; iii) a plurality of upright columns supporting a first set of horizontal grid members and a second set of horizontal grid members, the plurality of upright columns forming a plurality of vertical storage locations for containers to be stacked between the upright columns; Equipped with b) comparing the collected acceleration data with ground acceleration data from one or more accelerometers located on the ground surface; c) determining a differential acceleration between the acceleration data and the ground acceleration data; d) determining displacement data from the differential acceleration; e) determining whether a seismic event has occurred over a given time period based on the displacement data; The present invention provides a method comprising:

[0020] The acceleration data is collected from one or more accelerometers as a signal of acceleration as a function of time. A differential acceleration is calculated by subtracting the ground acceleration data from the acceleration data, and is the difference between the acceleration data and the ground acceleration data. The differential acceleration represents the acceleration of the grid framework structure relative to the ground.

[0021] The given time period represents the time between the start of the earthquake event and the end of the earthquake event. For example, the given time period may be the time during which the acceleration measured by the accelerometer is significantly higher than the background acceleration, or the time period during which the differential acceleration is above a minimum acceleration threshold.

[0022] The step of determining the displacement data may comprise performing a double integration on the differential acceleration data. Integrating the differential acceleration once with respect to time gives the differential velocity (the velocity of the grid framework structure with respect to the ground). Integrating the differential acceleration a second time, i.e. integrating the differential velocity with respect to time, gives the displacement data. The displacement data represents the differential displacement (the displacement of the grid framework structure with respect to the ground as a result of the movement of the grid framework structure) and is a signal of the displacement as a function of time. The acceleration data and the displacement data represent the acceleration and displacement of a point on the grid structure where each of the one or more accelerometers is located with respect to the ground. The ground acceleration data represents the acceleration of the ground since the ground acceleration data is collected from one or more accelerometers located on the ground and provides a reference point for calculating the differential acceleration data.

[0023] The one or more accelerometers located above the ground may be attached to a substructure (e.g., a concrete foundation or slab) on which the grid framework structure is built, or alternatively, the one or more accelerometers located above the ground may be placed directly on top of the soil (e.g., located inside a hole in the substructure).

[0024] The step of determining whether an earthquake event has occurred includes: a) detecting a non-proportional response from displacement data; b) detecting period elongation in the displacement data; c) calculating the static displacement from the displacement data; The signal may comprise one or more of:

[0025] In each of these three cases a), b) and c), the step of determining whether a seismic event has occurred may comprise identifying the presence of one or more characteristic vibration regimes in the displacement data, where the one or more characteristic vibration regimes are: a) A non-proportional response region; b) a periodic extension region; c) Residual drift region and Equipped with.

[0026] In each of these three cases a), b) and c), determining whether a seismic event has occurred may comprise comparing the displacement data, or a parameter derived from the displacement data, to a predetermined threshold. In case a) non-proportional response, the predetermined threshold may comprise a displacement threshold, in case b) period stretching, the predetermined threshold may comprise a predetermined frequency and / or a predetermined period of vibration, and in case c) residual drift, the predetermined threshold may comprise a predetermined static displacement threshold. Each of these three characteristic vibration regions is described in more detail below.

[0027] Case a), the non-proportional response region, can occur when the structural members of the grid framework structure extend beyond their elastic limits and exhibit inelastic behavior.

[0028] Determining whether a seismic event has occurred over a given period of time may comprise determining whether the displacement data exceeds a predetermined displacement threshold corresponding to an elastic limit of a member of the grid structure. Determining whether a seismic event has occurred may comprise identifying a non-proportional response region by determining whether the displacement is proportional to the acceleration.

[0029] Case b), the periodic elongation region, can occur when structural members deflect, thereby changing the dynamic properties of the grid framework structure.

[0030] The step of determining whether a seismic event has occurred may comprise determining a change in a frequency and / or period of vibration of the displacement data over a given period of time. Determining a change in a frequency and / or period of vibration of the displacement data may comprise determining whether a frequency and / or period of vibration differs from a predetermined frequency and / or a predetermined period of vibration. The step of determining a change in a frequency and / or period of vibration of the displacement data may comprise calculating a Fourier transform of the displacement data to obtain a frequency spectrum of the grid framework structure. The method may further comprise the steps of providing reference displacement data representative of a behavior of the grid framework structure in the absence of a seismic event and calculating a Fourier transform of the reference displacement data to obtain a reference frequency spectrum of the grid framework structure. The method may further comprise the steps of comparing the frequency spectrum of the grid framework structure to the reference frequency spectrum of the grid framework structure. A natural frequency of vibration of the grid structure may be obtained from the frequency spectrum of the grid framework structure. If the natural frequencies obtained from the reference frequency spectrum of the grid framework structure (i.e., the natural frequencies in the absence of a seismic event) differ from the natural frequencies obtained from the frequency spectrum of the grid framework structure, the change in the natural frequencies may be an indication of deflection in the grid framework structure.

[0031] Case c), a residual drift region, can occur when there is a static displacement of the grid framework structure that remains after the vibrations have subsided, i.e., the static displacement indicates that the accelerometer has moved from its initial position.

[0032] The displacement data can be divided into two parts: vibration or dynamic displacement, which represents the vibration of the accelerometer about its central position, and static displacement, which represents the movement of the central position of the vibration displacement relative to its origin or initial position. The dynamic displacement indicates that the position of the accelerometer is vibrating about its central position, and the static displacement indicates that the accelerometer has moved or been displaced from its origin or initial position. The displacement data is a superposition of the vibration displacement and the static displacement.

[0033] The step of determining whether a seismic event has occurred over a given period of time may comprise determining a static displacement from the displacement data and determining whether the static displacement exceeds a predetermined static displacement threshold.

[0034] If the central position of the vibration displacement remains at the origin, the static displacement is zero. However, if the structural member to which the accelerometer is attached flexes, the accelerometer will move and thus its central position of vibration displacement will no longer be at the origin or initial position of the accelerometer. This movement of the central position may also be described as residual drift, which means that after the vibration displacement subsides or decays, the accelerometer has been displaced (i.e., drifted) from its initial position.

[0035] Rather than determining whether a seismic event has occurred from the presence of a non-zero static displacement or residual drift, it is advantageous to define a predefined static displacement threshold greater than 0. When the static displacement exceeds this predefined static displacement threshold, a seismic event is deemed to have occurred. A predefined static displacement of 0 would pick up small displacements and cause false alarms (e.g., measurement errors) due to small displacements that are not caused by a seismic event.

[0036] Any or all of the three cases a), b) and c) may be used to determine if a seismic event has occurred. In some cases it may be advantageous to use two or more of these methods to ensure that the event is in fact a seismic event rather than a false positive (e.g. residual drift / static displacement may be detected if the accelerometer moves relative to the grid framework structure rather than indicating a failure of the structural member to which the accelerometer is attached).

[0037] The method may further comprise filtering the acceleration data to remove or attenuate one or more signals associated with non-seismic events. Non-seismic events that may cause seismic signals may include normal operation of storage and retrieval systems or other machinery in the same building or in the surrounding area. For example, seismic motion may be generated by load handling devices moving on a grid framework structure, or conveyor systems, pick stations, moving vehicles (e.g., forklift trucks), or other machinery in the same building. Outside the building, seismic motion may be generated by passing traffic, road construction, or ground movement. Filtering out these non-seismic signals is advantageous because the filtered data is cleaner and less likely to result in false positives (i.e., the method detects a seismic event when one did not occur).

[0038] Filtering the acceleration data may comprise using a high-pass filter, a low-pass filter, and / or a band-pass filter. A high-pass filter removes or attenuates signals at frequencies below a threshold frequency and allows signals at frequencies above the threshold frequency to pass. A low-pass filter removes or attenuates signals at frequencies above a threshold frequency and allows signals at frequencies below the threshold frequency to pass. A band-pass filter removes or attenuates signals at frequencies below a lower threshold frequency or above an upper threshold frequency and allows signals at frequencies between a lower threshold frequency and an upper threshold frequency to pass. Filtering is advantageous because it can remove noise at frequencies other than the frequency range of interest, e.g., the frequency range in which the seismic event occurs or the frequency range in which the signal may change as a result of the seismic event.

[0039] The step of filtering the acceleration data to remove or attenuate one or more signals associated with non-seismic events may comprise determining frequency ranges in which vibrations occurred in the absence of a seismic event and attenuating or filtering out these frequency ranges from the acceleration data.

[0040] The step of filtering the acceleration data to remove or attenuate one or more signals associated with a non-seismic event may comprise providing baseline acceleration data representative of behavior of the grid framework structure in the absence of a seismic event, determining frequency ranges in the baseline acceleration data in which vibrations occur in the absence of a seismic event, and attenuating or filtering out these frequency ranges from the acceleration data.

[0041] Determining which frequency ranges to filter out may be done by taking a Fourier transform of the acceleration and / or reference acceleration data to obtain a frequency spectrum.

[0042] The one or more accelerometers located on the grid framework structure may comprise multiple accelerometers, and determining whether a seismic event has occurred may be based on displacement data from the multiple accelerometers.

[0043] The advantage of using multiple accelerometers located on the grid framework structure is that there is redundancy added to the method. If the first accelerometer is unable to detect an earthquake event, the second accelerometer is performing the same task and can detect the earthquake event if the first accelerometer does not. If the method relied only on a single accelerometer located on the grid framework structure, the problems with the single accelerometer would mean that the earthquake event would go undetected.

[0044] In some examples with multiple accelerometers located on a grid framework structure, a voting system may be used to determine if an earthquake event has occurred. Each accelerometer will vote "yes" or "no" depending on whether the data collected by that accelerometer positively identifies an earthquake event. For example, if a majority of the multiple accelerometers vote "yes" (i.e., data from a majority of the multiple accelerometers positively identifies that an earthquake event has occurred), an earthquake event may be deemed to have occurred. A threshold for determining if an earthquake event has occurred may be based on a percentage of the multiple accelerometers voting "yes," which may be a number of accelerometers (e.g., at least 10 accelerometers) or a percentage of the total number of accelerometers (e.g., a majority or 50%, two out of three, 75%).

[0045] The step of determining whether an earthquake event has occurred may comprise at least two of three of the plurality of accelerometers detecting an earthquake event, where if there are three accelerometers located on a grid framework structure, an earthquake event will be deemed to have occurred if a first accelerometer and a second accelerometer vote "yes" but a third votes "no."

[0046] The method may further comprise sending a signal to one or more output devices in response to determining that an earthquake event has occurred for a given period of time, which is important to alert personnel to the earthquake event so that they can be evacuated from the building.

[0047] The method comprises: a) Whether the grid framework structure has been permanently deformed; and / or b) Whether the grid framework structure is sufficiently intact to continue to operate; and / or c) Whether the grid framework structure is safe for personnel to enter; and / or d) Whether the grid framework structure has the structural capacity to withstand aftershocks. The method may further comprise using the differential acceleration and / or displacement data to determine:

[0048] These different states of the grid framework structure are explained in more detail later.

[0049] In examples where the one or more accelerometers comprise multiple accelerometers distributed across the grid framework structure, the method may further comprise using differential acceleration and / or displacement data to determine the extent of damage to different parts of the grid framework structure.

[0050] The method may further comprise preparing the grid framework structure for further seismic activity if the method detects an early stage of a seismic event.

[0051] The step of preparing the grid framework structure for a seismic event includes: cutting off power to components of the grid framework structure; deactivating a load handling device operable on the grid framework structure; activating a brake on the load handling device; cutting off power to a load handling device operable on the grid framework structure; The signal may comprise one or more of:

[0052] Alternatively or additionally, preparatory actions may be taken as a result of an alert from an earthquake early warning system, sometimes known as an Earthquake Early Warning (EEW) or Early Warning System (EWS). Such systems operate on the principle that electronic alerts from the region of the epicenter of a seismic event can travel more quickly than seismic waves. During a seismic event, P waves (pressure waves or first waves) are followed by S waves (shear waves or second waves). P waves are longitudinal compressional waves that travel faster than S waves and can be transmitted through liquid layers in the Earth's interior. S waves are transverse shear waves that are more destructive than P waves, but travel more slowly. When a seismic event occurs, the initial P waves trigger sensors that detect their presence. The location and magnitude of the seismic event are estimated from the P waves, and the system sends alerts to affected areas. Locations farther from the epicenter of the seismic event can have seconds or minutes to prepare before the more destructive S waves arrive. The combination of early warning systems and automated responses can help prevent some of the injuries and damage commonly associated with large earthquake events.

[0053] As a result of an alert from the earthquake early warning system, appropriate actions may be taken. For example, personnel may be evacuated from buildings housing the grid framework structure, vehicles may be parked, power sources (e.g., engines or motors) may be switched off, and other machinery may be turned off or shut down. Additionally, the steps described above for preparing the grid framework structure are applicable.

[0054] In another aspect, the present invention provides a method of condition monitoring a grid framework structure following a seismic event, the grid framework structure comprising: i) a first set of horizontal grid members extending in a first direction; ii) a second set of horizontal grid members extending in a second direction substantially perpendicular to the first direction and intersecting the first set of horizontal grid members at an intersection, the first set of horizontal grid members and the second set of horizontal grid members being arranged to form a grid comprising a plurality of substantially rectangular frames in a horizontal plane, each of the substantially rectangular frames defining a grid cell; iii) a plurality of upright columns supporting a first set of horizontal grid members and a second set of horizontal grid members, the plurality of upright columns forming a plurality of vertical storage locations for containers to be stacked between the upright columns; iv) one or more accelerometers located on the grid framework structure; Equipped with The method comprises: a) collecting acceleration data from one or more accelerometers over a given period of time; b) comparing the collected acceleration data with ground acceleration data over a given period of time from one or more accelerometers located on the ground surface; c) determining a differential acceleration between the acceleration data and the ground acceleration data; d) determining the extent of damage to different portions of the grid framework structure that occurred during a given time period by determining whether the differential acceleration data exceeds a predetermined acceleration threshold during the given time period; The present invention provides a method comprising:

[0055] The purpose of the condition monitoring is to determine the condition of the grid framework structure after a seismic event, for example, the extent of damage to different parts of the grid framework structure. Condition monitoring after a seismic event is important to assess the extent of damage to different parts of the grid framework structure, which will allow the grid framework structure to be repaired faster and reduce downtime. Without condition monitoring, the entire grid framework structure would need to be assessed for damage, and more importantly, there would be no indication of whether the grid framework structure is safe for personnel to enter. The predefined acceleration threshold is the acceleration value used to define the status of a portion of the grid framework structure, i.e., different actions (e.g., inspection, repair) may be required depending on whether the differential acceleration exceeds the predefined acceleration threshold or not.

[0056] The predetermined acceleration threshold may comprise a plurality of predetermined acceleration thresholds, each of the plurality of predetermined acceleration thresholds indicating a different level of damage to one or more of the portions of the grid framework structure, which allows different portions of the grid framework structure to be classified or categorized according to their level of damage such that appropriate action (e.g., inspection and / or repair) can be efficiently undertaken.

[0057] The plurality of predetermined acceleration thresholds may comprise a first acceleration threshold indicative of an elastic limit of the portion of the grid framework structure, such that a differential acceleration of the portion of the grid framework structure exceeding the first acceleration threshold provides an indication that the portion of the grid framework structure has been permanently deformed. If permanently deformed, the portion of the grid framework structure may not be in a suitable condition to continue to operate, e.g., the load handling device may not be able to move on a deformed or misaligned track, the load handling device may not be able to lift a storage container from a stack if the vertical uprights are deformed or misaligned. If not permanently deformed, the portion of the grid framework structure may be in a suitable condition to continue to operate, e.g., the track has returned to its original shape and position, and thus the load handling device can still operate on the track, and the vertical uprights have returned to their original shape and position, and thus the load handling device can continue to lift a storage container from a stack to retrieve products for customer orders.

[0058] The first acceleration threshold may be substantially 0.6 g.

[0059] The plurality of predetermined acceleration thresholds may comprise a second acceleration threshold indicative of a safety limit, such that a differential acceleration of the portion of the grid framework structure that exceeds the second acceleration threshold provides an indication that the portion of the grid framework structure is unsafe for personnel to enter. Understanding which portions of the grid framework structure are safe for personnel to enter is advantageous for both reducing risk to personnel and enabling personnel to confidently and safely inspect portions of the grid framework structure that are safe for personnel to enter.

[0060] The second acceleration threshold may be substantially 1.0 g.

[0061] The plurality of predetermined acceleration thresholds may comprise a third acceleration threshold indicative of a structural limit, such that a differential acceleration of a portion of the grid framework structure exceeding the third acceleration threshold provides an indication that the portion of the grid framework structure does not have sufficient structural capacity to withstand an aftershock. The structural limit is a measure of whether the portion of the grid framework structure has sufficient structural capacity to withstand an aftershock, i.e., if the differential acceleration remains below the structural limit, the portion of the grid framework structure is capable of withstanding an aftershock, and if the differential acceleration exceeds the structural limit, the portion of the grid framework structure is not capable of withstanding an aftershock and is therefore at risk of collapsing as a result of the aftershock. If the third acceleration threshold is exceeded, no personnel should enter the grid framework structure.

[0062] The third acceleration threshold may be substantially 1.83 g.

[0063] The method comprises: f) determining displacement data from the differential acceleration; g) determining the extent of damage to different parts of the grid framework structure by determining whether the displacement data exceeds a predetermined displacement threshold; The device may further include:

[0064] The predetermined displacement threshold may indicate an elastic limit, such that a displacement of a portion of the grid framework structure beyond the predetermined displacement threshold provides an indication that the portion of the grid framework structure has been permanently deformed. If the displacement of the portion of the grid framework structure falls below the predetermined displacement threshold, the elastic limit has not been exceeded and the portion of the grid framework structure has elastically deformed and returned to its original position. This may indicate that the portion of the grid framework structure can continue to operate normally, i.e., the truck supporting the load handling device is not misaligned and therefore can continue to be used. Knowing which portions of the grid framework structure have not exceeded their elastic limit is advantageous, since some portions may be able to continue to operate normally, while other portions are assessed for damage and repaired as necessary. Ensuring business continuity, i.e., being able to continue to fulfill customer orders, is a major advantage.

[0065] In another aspect, the present invention provides an earthquake detection system for a grid framework structure configured to perform the method of any of the above aspects, the earthquake detection system comprising: a) one or more accelerometers mounted on a grid framework structure; b) an input module configured to collect acceleration data from one or more accelerometers; c) a controller in communication with the input module, the controller comprising one or more processors and a memory storing instructions, the instructions, when executed by the one or more processors, causing the one or more processors to: i) determining whether a seismic event has occurred based on the collected acceleration data from the one or more accelerometers; ii) in response to determining that a seismic event has occurred, sending a signal to one or more output devices; To carry out An earthquake detection system is provided, comprising:

[0066] In some cases, the input module may also provide power to the accelerometer.

[0067] The earthquake detection system may further include an output module configured to enable the controller to send a signal to one or more output devices.

[0068] The earthquake detection system may further include one or more accelerometers located on the ground near the grid framework structure that may be used to collect ground acceleration data to be used as a reference in calculating the differential acceleration data, as described above.

[0069] The one or more output devices may include a beacon, an alarm, and / or a siren.

[0070] In another aspect, the present invention provides a method for producing a composition comprising: a first set of horizontal grid members extending in a first direction; a second set of horizontal grid members extending in a second direction substantially perpendicular to the first direction and intersecting the first set of horizontal grid members at an intersection; and the first set of horizontal grid members and the second set of horizontal grid members arranged to form a grid comprising a plurality of substantially rectangular frames in a substantially horizontal plane, each of the substantially rectangular frames defining a grid cell. a plurality of upright columns supporting a first set of horizontal grid members and a second set of horizontal grid members, the plurality of upright columns forming a plurality of vertical storage locations for containers to be stacked between the upright columns; A grid framework structure comprising: There is provided a grid framework structure, wherein the grid framework structure further comprises an earthquake detection system of the present invention.

[0071] The one or more accelerometers mounted on the grid framework structure may comprise a plurality of accelerometers arranged along a first direction and / or a second direction of the grid. For example, the first direction may represent an X direction and the second direction may represent a Y direction perpendicular to the X direction. The accelerometers may be arranged in one or more lines along the X direction and / or the Y direction or arranged in a grid pattern. The plurality of accelerometers may be arranged along at least a portion of the periphery of the grid. For example, the plurality of accelerometers may be arranged in a line along one edge of the grid, or two edges of the grid, or three edges of the grid, or all four edges of the grid. In some examples, a portion of the plurality of accelerometers may be arranged on the periphery of the grid and the remainder of the accelerometers may be arranged within the grid. At least a portion of the plurality of accelerometers may be arranged in a diagonal direction with respect to the first and second directions of the grid. For example, a portion of the plurality of accelerometers may be arranged in a diagonal across the grid. Combinations of these and other arrangements are also possible.

[0072] The accelerometers may be in a substantially horizontal plane. They may be in the same plane as the grid itself (e.g., mounted on a track or on a horizontal grid member) or in a parallel horizontal plane. They may be located at or near the top of the grid framework structure to measure differential acceleration between the top of the grid framework structure and the ground.

[0073] The advantage of having multiple accelerometers distributed horizontally on the grid framework structure is that the accuracy of the data is improved: a greater number of accelerometers allows the displacement of the grid framework structure to be determined with greater accuracy and in more detail.

[0074] An additional benefit of having multiple accelerometers distributed horizontally on the grid framework structure is that data from the accelerometers can be used to determine which part(s) of the grid framework structure sustained damage in a seismic event. If one part of the grid framework structure is damaged but another part remains intact, it may be possible for a load handling device to continue to operate on the undamaged part of the grid while the damaged part is repaired. Accelerometer data can also be used to determine the extent of deflection / damage to the grid framework structure, for example, whether a part of the grid framework structure has not exceeded its elastic limit and can continue to operate as normal, or whether it has been damaged but is safe for personnel to enter and assess the situation and take corrective action, or whether it has been damaged to the point that it is unsafe for personnel to enter that area of ​​the grid framework structure.

[0075] The plurality of accelerometers may consist of between 15 and 28 accelerometers.

[0076] One or more accelerometers mounted on a grid framework structure may be mounted on horizontal grid members, in some examples, the accelerometers may be mounted on the track, on track supports, or on vertical uprights.

[0077] The grid framework structure may further comprise an exoskeleton comprising a plurality of vertical frame columns braced by one or more bracing members, the grid being further supported by the exoskeleton to form a seismic force restraint system (SFRS). As described in more detail below, the exoskeleton provides further support to the grid framework structure and protects it from damage in the event of a seismic event.

[0078] One or more accelerometers mounted on the grid framework structure may be mounted on the SFRS. In particular, one or more accelerometers mounted on the grid framework structure may be attached to one or more brace members. The brace members act as sacrificial members in the event of an earthquake event (i.e., they will deflect first, protecting the grid framework structure from damage), and therefore, by placing accelerometers on the brace members, the earthquake detection system is able to detect whether the brace members are deflecting. If the brace members are not deflecting, the grid and supporting framework structure are intact and can continue to operate. It is advantageous to be able to determine that a part of the grid is undamaged and can continue to operate, because then at least a portion of the storage system can continue to fulfill customer orders without significant downtime, thus reducing costs and allowing business continuity.

[0079] The grid framework structure may be subdivided into a plurality of modular frames, such that the grid extends across the plurality of modular frames. In instances where the grid framework structure is modular, some or all of the modular frames may be supported by an exoskeleton. Each of the plurality of modular frames may include an exoskeleton comprising a plurality of vertical frame columns braced by one or more bracing members, and the grid is supported by the exoskeleton to form a seismic force suppression system (SFRS), where adjacent modular frames are arranged such that at least a portion of the SFRS is shared between adjacent modular frames.

[0080] Another way to describe the modular grid framework structure is as an assembly comprising a plurality of modular frames, where each of the plurality of modular frames comprises the grid framework structure, a grid extends across the plurality of modular frames, and at least one of the plurality of modular frames comprises the earthquake detection system described above.

[0081] An advantage of subdividing the grid framework structure into multiple modular frames is that if one of the modular frames is deflected due to a seismic event, the other modular frames may be unaffected and able to continue operating.

[0082] The grid framework structure may further comprise a seismic isolation system for reducing seismic forces acting on the grid framework structure, wherein the grid framework structure is supported by the seismic isolation system, the seismic isolation system comprising a superstructure, a substructure, and at least one base isolation device disposed between the superstructure and the substructure, such that the at least one isolation device inhibits movement of the superstructure relative to the substructure in a seismic event.

[0083] Earthquake isolation systems have the advantage of partially isolating or decoupling the grid framework structure from its foundations, so that the horizontal component of ground movement during a seismic event is attenuated. At least one isolation device allows for relative movement between the superstructure and substructure, so that not all of the horizontal movement of the ground is translated into horizontal movement of the grid framework structure.

[0084] In another aspect, the present invention provides a method for producing a composition comprising: i) a first grid framework structure at a first level; ii) a second grid framework structure at a second level, the second level being above the first level; A multi-storey grid framework structure comprising: There is provided herein a multi-storey grid framework structure, wherein a first grid framework structure and a second grid framework structure each comprise a grid framework structure as defined herein.

[0085] The advantage of a multi-storey grid framework structure is that it provides more storage space for the same footprint, which is particularly useful in territories where available land is at a premium and therefore there is an advantage to building upwards rather than outwards, which makes the most efficient use of available space.

[0086] In another aspect, the present invention provides a method for producing a composition comprising: A grid framework structure as defined herein; one or more load handling devices remotely operable to move one or more containers stored in the grid framework structure, each of the one or more load handling devices comprising: i) a wheel assembly for guiding a load handling device on the grid framework structure; ii) a container receiving space located above the grid framework structure; and iii) a lifting device arranged to lift a single container from the stack and into the container receiving space; Equipped with A storage and retrieval system is provided, comprising:

[0087] Additional features and aspects of the present invention will become apparent from the following detailed description of illustrative embodiments that proceeds with reference to the drawings. [Brief description of the drawings]

[0088] [Figure 1]1 is a schematic diagram of a grid framework structure according to a known system; [Diagram 2] FIG. 2 is a schematic diagram of a top-down view showing a stack of bins arranged within the framework structure of FIG. 1. [Diagram 3] 1 is a schematic diagram of a known system of load handling devices operating on a grid framework structure. [Figure 4] FIG. 2 is a schematic perspective view of a load handling device showing a lifting device gripping a container from above. [Figure 5(a)] 5(a) is a schematic perspective cutaway view of the load handling device of FIG. 4 showing a container accommodated within the container receiving space of the load handling device; FIG. [Figure 5(b)] 5(b) is a schematic perspective cutaway view of the load handling device of FIG. 4, showing the container receiving space of the load handling device; [Figure 6] 1 is a perspective view of a grid framework structure according to one embodiment of the present invention; [Figure 7] 1 is a perspective view of a cap plate for joining adjacent grid elements at their intersections, according to one embodiment of the present invention; FIG. [Figure 8] 1 is a perspective view of a cap plate linking adjacent grid elements by connecting the ends of the grid elements at their intersections, according to one embodiment of the present invention; FIG. [Figure 9] 13 is a perspective view of a cap plate linking adjacent grid elements at their intersections by connecting a central section of a grid element with an end of an adjacent grid element, in accordance with an embodiment of the present invention; FIG. [Figure 10] 1 is a perspective view of a cap plate fitted to an upright column for connecting adjacent grid elements to each other at the intersections where the grid elements cross, according to one embodiment of the present invention. FIG. [Figure 11] 4 is a perspective view illustrating a pattern of grid elements at an intersection, according to one embodiment of the present invention. [Figure 12(a)] 1 is a schematic diagram of a braced tower, according to one embodiment of the present invention. [Figure 12(b)] 1 is a schematic diagram of a brace tower according to one embodiment of the present invention. [Figure 13] FIG. 2 is a perspective view of an adjustable foot, according to one embodiment of the present invention. [Figure 14] 1A and 1B are side and top views of an anchor foot according to a second embodiment of the present invention; [Figure 15] 1 is a perspective view of a seismic grid framework structure according to a first embodiment of the present invention; [Figure 16] Schematic diagram of the main hardware components of the earthquake detection system. [Figure 17] FIG. 1 illustrates a possible arrangement of an earthquake detection system architecture where post-event data processing occurs in the cloud. [Figure 18(a)] 1A-1C are schematic plan views of a grid structure showing different options for the location of accelerometers on the grid structure. [Figure 18(b)] 1A-1C are schematic plan views of a grid structure showing different options for the location of accelerometers on the grid structure. [Figure 19] 3 is a flow chart illustrating steps in a method for detecting earthquake events, according to one embodiment of the present invention. [Figure 20] Graph of exemplary displacement data showing non-proportional response, periodic elongation, and residual drift region. [Figure 21] 2 is a schematic diagram of a controller and other components of an earthquake detection system, in accordance with one embodiment of the present invention. [Figure 22] A floor plan showing the modularity of the grid framework construction. [Diagram 23] Schematic plan view of a modular grid structure with pick aisles and mezzanines. [Figure 24] 24 is a schematic plan view of the grid structure of FIG. 23 showing the placement of accelerometers on diagonals on the grid structure. [Diagram 25] 24 is a schematic plan view of the grid structure of FIG. 23 showing the placement of accelerometers on diagonals on the grid structure. [Figure 26]24 is a schematic plan view of the grid structure of FIG. 23 showing the placement of accelerometers on two sides of the grid structure. [Figure 27] 24 is a schematic plan view of the grid structure of FIG. 23 showing the placement of accelerometers on two sides of the grid structure. [Figure 28] 24 is a schematic plan view of the grid structure of FIG. 23 showing the placement of accelerometers on four sides of the grid structure. [Figure 29] 27 is a schematic plan view of the grid structure with the accelerometer placement shown in FIG. 26 showing the approximate location of the damage on the grid structure. [Diagram 30] Schematic diagram of (a) a single storey storage system and (b) a multistorey storage system. [Diagram 31] 1 is a cross-sectional view of a portion of a seismic isolation system showing the isolation device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0089] [Grid framework structure] FIG. 6 shows a perspective view of a grid framework structure 114 according to an embodiment of the present invention. The basic component of the grid framework structure 114 according to the present invention comprises a grid or grid structure 50 in a horizontal plane attached to a number of upright columns or members 116. The terms "upright member(s)" and "upright column(s)" are used interchangeably herein to mean the same thing. As shown in FIG. 6, the grid 50 comprises a series of horizontal cross beams or grid members 118, 120 arranged to form a number of rectangular frames 54, more specifically, a first set of grid members 118 extending in a first direction x and a second set of grid members 120 extending in a second direction y, the second set of grid members 120 extending transversely to the first set of grid members 118 in a substantially horizontal plane. Each of the grid members extending in the first direction and / or the grid members extending in the second direction may be subdivided or sectioned into individual grid elements that are joined or linked to each other.

[0090] As an alternative to the grid framework structure 114 directly supporting the two-dimensional grid 50 on a plurality of upright columns 116 as described with reference to FIG. 6, in another example, the grid framework structure 114 supports the grid 50 on top of a plurality of prefabricated modular panels arranged in a grid pattern, the details of which are described briefly below and in full in PCT application WO2022034195A1 in the name of Ocado Innovation Ltd, which is incorporated herein by reference. This grid framework structure described in WO2022034195A1 addresses the problem of time and cost to assemble by supporting a 2D grid on a supporting framework structure comprising a plurality of prefabricated modular panels arranged in a three-dimensional grid pattern to define a plurality of grid cells. Each of the grid cells of the supporting framework structure is sized to support two or more grid cells of the grid on which the load handling device operates. The grid framework structure is formed from fewer structural components, yet maintains the same structural integrity as the typical "stick-built" grid framework structure 114 described above, and is much faster and cheaper to construct.

[0091] The prefabricated modular panels of the grid framework structure described above comprise upright columns 116. For example, subgroups of upright columns may be braced by one or more bracing members to form a prefabricated panel or frame. For purposes of the present invention, a plurality of upright columns 116 may also include upright columns 116 in a prefabricated panel. The grid framework structure 114 may comprise any suitable supporting framework structure for supporting the grid, including upright columns 116 that directly support the grid, and / or prefabricated panels and / or frames that incorporate the upright columns 116.

[0092] A connecting plate or cap plate 150 shown in Figure 7 may be used to link or join the individual grid elements together in both the first and second directions at the junctions where the grid elements crisscross or intersect in each of the upright columns, i.e., the cap plate 150 is used to connect the grid elements together in the upright columns 116. As a result, the upright columns are interconnected at the upper ends of the upright columns at the junctions where the grid elements crisscross in the grid structure by the cap plate 150. As shown in Figure 7, the cap plate 150 is cross-shaped and has four connecting portions 152 for connecting at the intersections of the grid elements, at the ends of the grid elements, or anywhere along the length of the grid elements (see Figures 8 and 9). The cap plate 150 includes a spigot or protrusion 154 sized to fit snugly into the hollow central section 70 of the upright column 116 (at the second end of the upright column) to interconnect multiple upright columns to the grid members, as shown in Figure 10. Figure 13 illustrates a joint at the intersection between adjacent grid elements at the upper ends of the upright columns with one or more cap plates. For purposes of illustration, the lower end of the upright column attached to the floor forms the first end of the upright column, and the upper end of the upright column adjacent the grid 50 forms the second end of the upright column.

[0093] The first set of grid members and the second set of grid members support a first set of tracks or rails 22a and a second set of tracks or rails 22b, respectively, for a load handling device to move one or more containers on the grid framework structure. In some examples, the tracks 22a, 22b may be integral with the grid members. In other examples, the tracks may be attached to the top of the grid members (also known as track supports). For purposes of this description, the intersections 56 form nodes of the grid structure. Each of the rectangular frames 54 forms a grid cell and is sized for a remotely operated load handling device or bot to travel on the grid framework structure to pick and drop one or more containers stacked between the upright columns 116. The grid 50 is elevated above ground level by the grid members 118, 120 being attached to a plurality of upright columns 116 at crisscross intersections or nodes 56 to form a plurality of vertical storage locations 58 for containers to be stacked between and guided by the upright columns 116 vertically through a plurality of substantially rectangular frames 54. For purposes of the present invention, a stack of containers may encompass a plurality of containers or one or more containers.

[0094] The grid framework structure 114 may be considered as a free-standing (or self-supporting) linear collection of upright columns 116 that support the grid 50 formed from intersecting horizontal grid members 118, 120, i.e., a four-walled framework. Two or more of the upright columns are braced by at least one diagonal brace member to provide one or more brace towers 80 within the grid framework structure 114. The structural stiffness and moment resistance of the grid framework structure is provided in large part by incorporating one or more truss assemblies or brace towers 80 at least partially around the periphery of the grid framework structure and / or within its body (see FIG. 6). The truss assemblies may have a triangular or other non-trapezoidal shape. For example, the truss assemblies may be any type of truss that provides structural stiffness to the grid framework structure against lateral forces, including, but not limited to, a Warren truss or a K truss or a Fink truss or a Pratt truss or a Gambrel truss or a Howe truss. Bolts or other suitable attachment means may be used to fasten the diagonal braces to the upright columns. The brace tower 80 shown in FIG. 12 according to one embodiment of the present invention may be formed by rigidly connecting a subset or subgroup of multiple upright columns 116 by one or more angled or diagonal braces or diagonal brace members 82. For purposes of the present invention, the diagonal braces 82 cooperate with the upright columns 116 in the brace tower 80 to form one or more triangles. The subset of multiple upright columns braced together to form the brace tower 80 of the present invention may be two or more adjacent upright columns 116 that lie in the same or a single vertical plane and that are connected together by one or more diagonal braces 82. Stated differently, two or more adjacent upright columns 116 connected by one or more diagonal braces 82 lie in the same or a single vertical plane, i.e., they are coplanar.In a particular embodiment of the invention shown in FIG. 12, each brace tower 80 comprises three upright columns in parallel relationship, lying in a single vertical plane (coplanar), which are rigidly connected to one another by a plurality of diagonal braces 82. Two of the three upright columns 116a, 116b are disposed laterally on either side of a middle upright column 116c, and the two laterally disposed upright columns 116a, 116b are rigidly connected to the middle upright column 116c by a plurality of diagonal braces 82. In the brace tower 80 of the invention, one end of the diagonal brace member 82 is connected to the middle upright column by a joining plate 121. The joining plate 121 is slotted through a hollow central section of the middle upright column 116c in a direction perpendicular to the longitudinal direction of the upright columns. The structural rigidity of the grid framework structure is improved by bracing one or more subgroups of upright columns 116 internally within the grid framework structure with one or more diagonal braces 82. For purposes of the present invention, the terms "vertical upright column", "upright column" and "upright member" are used interchangeably throughout the description.

[0095] The grid framework structure is anchored to the ground, in this case to the superstructure, by one or more anchor bolts. In one embodiment of the invention, one or more of the upright columns are attached to the superstructure at their lower ends by adjustable feet (see FIG. 13). The adjustable feet allow the height of one or more of the upright columns, and therefore the height of the grid framework structure as a whole, to be adjusted. This allows the level of the grid in the horizontal plane to be substantially flat for load handling devices, which are mostly remotely operated to proceed on the grid structure, and thereby prevents any of the tracks or rails from being subjected to distortion due to variations in the height of one or more of the upright members 116 in the grid framework structure. The adjustable foot 90 shown in FIG. 13 comprises a base plate 92 and a threaded spindle or rod 94 that is threadably engageable with a separate push-fit cap or plug 96 that is placed at the lower end of the upright column as shown in FIG. 8. As shown in FIG. 6, one or more of the upright columns 116 are attached to the floor or to the superstructure by the base plate 92. The base plate 92 has one or more mounting holes for attaching the base plate 92 to a floor by one or more bolts.

[0096] In addition to mounting the upright columns constituting the grid framework structure by the adjustable feet described above, one or more of the upright columns constituting the brace tower 80 are anchored to the superstructure by one or more anchor feet 132a, 132b (see FIG. 12). In the particular embodiment shown in FIG. 12, the outer upright columns 116a, 116b or the laterally disposed upright columns 116a, 116b are anchored to the concrete foundation by one or more anchor feet 132, and the middle upright column 116c is supported on the adjustable foot 90 described above. The lower end (first end) of the brace tower is anchored to the concrete foundation by one or more anchor bolts. Various types of anchor feet 132a, 132b for rigidly anchoring the brace tower to the concrete foundation are applicable in the present invention. The anchor foot functions to bear the upright column load and the bracing load of the brace assembly 82 of the brace tower 80.

[0097] Figures 12 and 14 show two examples of anchor feet used to anchor a brace tower to a concrete foundation according to the present invention. The anchor foot shown in Figure 12 is more substantial in terms of size and weight compared to the anchor foot shown in Figure 14. The anchor foot 132a shown in Figure 12 is made as a T-joint with a base plate 133 in a horizontal plane for anchoring to the floor by one or more anchor bolts and an anchor plate 134 perpendicular to the base plate 133 for attaching to the lower end of the upright column and the end of the brace member 82. The anchor plate 134 is oriented so that the surface of the anchor plate 134 with the largest surface area is in the same vertical plane as the three upright columns 116a, 116b, 116c of the brace tower 80, e.g., the surface of the anchor plate 134 with the largest surface area is coplanar with the upright members 116a, 116b, 116c of the brace tower 80. A problem with the anchor foot 132a shown in FIG. 12 is the substantial weight and therefore cost of making the anchor foot.

[0098] FIG. 14 shows an alternative anchor foot 132b for anchoring a brace tower 80 to a concrete foundation according to a second embodiment of the present invention. Instead of a solid rectangular base plate 133, the anchor foot is a topology optimized that optimizes the material layout within a given design space for a given set of loads. The two loads considered in the topology optimization of the anchor foot are the load from the upright columns 116a, 116b, 116c and the load from the brace member 82. Based on the constraints given by the applied loads, the anchor foot 132b of the present invention comprises a stabilizer 136 comprising a plurality of individual fingers or digits 138 extending from an upright portion 140, so that the load is distributed among the plurality of fingers 138, e.g., separate fingers. In the particular embodiment of the invention shown in FIG. 14, the upright portion 140 comprises an anchor plate arranged to rigidly connect to the upright columns 116a, 116b and the diagonal brace 82 by one or more bolts so as to support the load of the upright columns 116a, 116b and the applied load of the diagonal brace 82. Like the anchor plate 134 of the first embodiment of the invention shown in FIG. 12, the anchor plate 140 is oriented so that the surface of the anchor plate 140 with the largest surface area is in the same vertical plane as the three upright columns 116a, 116b, 116c that make up the brace tower 80 of the invention (see FIG. 7). Using the terminology of the invention, the surfaces of the upright columns 116a, 116b, 116c, the diagonal brace 82, and the anchor plates 134, 140 are all in the same plane, i.e., they are coplanar.

[0099] One or more of the individual fingers 138 of the anchor foot 132b extend or spread in two or more different directions from the upright portion 140 to provide improved stability of the anchor foot 132b. One or more of the fingers 138 are of different lengths to aid in the stability of the anchor foot 132b of the present invention. The lengths of the fingers 138 can be different and thus provide different levels of stability of the brace tower 80. One or more connecting webs 142 are used to support one or more of the fingers 138 from axial movement. The anchor foot 132b is anchored to a concrete foundation by one or more bolts through holes in the fingers 138 of the anchor foot 132b.

[0100] In a particular embodiment of the invention, five fingers 138 of varying lengths are shown extending from an upright portion 140 with holes at the distal ends of the fingers 138 for anchoring the anchor foot to the ground via an anchor bolt (see FIG. 14b). The anchor foot 132b, according to a second embodiment of the invention, may be formed as a single body, e.g., a casting, or separate parts joined together, e.g., a weldment. [Earthquake Framework Suppression System] The current grid framework structure 114 is sufficient when the ground is relatively stable, i.e., has a spectral acceleration of less than 0.33g, categorized as a Type A and Type B event, but this is not sufficient when the grid framework structure is subjected to a powerful earthquake event that generates strong lateral forces in excess of 0.55g spectral acceleration, categorized as a Type C or D earthquake event. Such a powerful earthquake event can fail the structural fasteners that connect the grid elements (e.g., track support elements) at the intersections, causing the structural fasteners to gradually loosen or come off the cap plates to which they are bolted. The result is a weakening or complete loss of structural integrity of the grid framework structure, as the lateral forces can no longer be safely transmitted down to the structural foundation. Failure may occur at the intersections of the grid members or track support elements that make up the grid. The braced towers 80 described above that are used to maintain the structural integrity of the grid framework structure may not be able to withstand the lateral forces resulting from a powerful Type D earthquake event that significantly exceeds 0.55g.

[0101] One way to alleviate the above problems is to support the grid framework structure by an exoskeleton, as described in WO2021175873 (Ocado), the contents of which are incorporated herein by reference. The exoskeleton provides an additional level of support to the grid framework structure from earthquake events. More specifically, the exoskeleton comprises a plurality of vertical frame columns 218 braced by at least one bracing member, and the grid is further supported by the exoskeleton to form a seismic force suppression system (SFRS).

[0102] The present invention provides an earthquake-restrained grid framework structure 214, as shown in FIG. 15, comprising a structural restraint system, sometimes known as a seismic force restraint system (SFRS), for maintaining the structural integrity of the grid framework structure of the present invention during strong earthquake and storm events, i.e., the SFRS supports the grid framework structure of the present invention against strong lateral forces as a result of type C and / or D earthquake events. The restraint system of the present invention reduces or eliminates failure of structural fasteners, such as joints that secure grid elements to upright columns through cap plates at intersections, due to breakage, loosening, detachment or fracture across structural components. The SFRS of the present invention comprises a perimeter brace structure 215 supported by a plurality of vertical frame columns 218 for supporting the grid against lateral forces. The perimeter brace structure 215 comprises at least one brace member 220, 222 extending from the plurality of vertical frame columns 218. For the purposes of the present invention, the term "support" is interpreted to cover any form of mechanical connection between the SFRS and the grid. For example, lateral forces generated at the grid level are transferred to the SFRS of the present invention at the perimeter of the grid 250. Further, for purposes of the present invention, the at least one brace member 220, 222 may be at least one horizontal frame beam between the vertical frame columns 218 and / or at least one diagonal brace member 222 between the vertical frame columns 218. For purposes of the present invention, the terms "vertical frame column" and "vertical support frame column" are used interchangeably herein to refer to the columns 218 supporting the brace members 220, 222. The vertical frame columns 218 are spaced apart by one or more spacers 74, unlike the vertical upright columns 116 supporting the grid, described above. The vertical frame columns 218 form part of the SFRS together with the perimeter brace structure of the present invention. The SFRS may be envisioned to form an exoskeleton around the grid framework structure.

[0103] The SFRS may be envisioned to form an exoskeleton around the grid framework structure of the present invention. In a specific embodiment of the present invention, the perimeter bracing structure 215 is supported by at least one vertical frame column 218a at the corners of the grid framework structure and is braced by at least one horizontal frame beam 220 extending from the corners of the grid framework structure. In a specific embodiment of the present invention shown in FIG. 15, four vertical frame support columns 218a are arranged at the four corners of the grid framework structure to form a three-dimensional exoskeleton, e.g., a rectangular parallelepiped structure, having a top surface and four sides. Since the SFRS forms an exoskeleton around the perimeter of the grid framework structure of the present invention, the vertical frame support columns 218a at the corners of the grid framework structure may be referred to as perimeter frame columns to simplify the description of the SFRS of the present invention. In a specific embodiment of the present invention, four horizontal frame beams 220 are attached to the top of each of the four perimeter frame columns 218a to extend from each corner of the SFRS frame. The horizontal frame beam 220 may be assumed to represent an upper chord that connects the two vertical frame columns 218a at their upper ends of the perimeter brace structure 215, and may be referred to as the perimeter frame beam.

[0104] At least two of the vertical frame columns 218a, 218b are connected together by at least one diagonal brace member 222 to form a brace frame to provide lateral support for the grid framework structure in the forward and / or aft directions. A brace frame is a structural system designed to withstand seismic forces. The diagonal brace members 222, like trusses, are designed to work in tension and compression and are designed to withstand lateral loads in the form of axial stresses, either by tension or compression. The brace frame may be placed around the perimeter of the grid framework structure or around at least one face of the grid framework structure and designed to absorb most of the lateral forces experienced by the grid framework structure.

[0105] Any type of brace frame commonly known in the art for providing lateral support to grids and / or grid framework structures is applicable in the present invention. In FIG. 15, the brace frame is a cross brace, where two diagonal braces 222 cross each other to form an X. The brace frame can also be a K brace, where two diagonal braces meet at an apex on a horizontal frame beam. Bracing at least two of the vertical frame columns 218a, 218b by at least one horizontal frame beam 220 at the top of the vertical frame columns 218a, 218b forms at least one drag strut or collector, commonly known in the art. The drag strut or collector is where at least two vertical frame columns 218a, 218b are braced by the horizontal frame beam 220 at the top of those two vertical frame columns 218a, 218b, and functions to collect and transfer diaphragm shear forces to the vertical frame columns.

[0106] Each of the plurality of vertical frame columns 218a, 218b may be a solid support of C-shaped or U-shaped cross section, double C or double U. Preferably, each of the plurality of vertical frame columns 218a, 218b is an I-shaped solid support with an upper beam flange and a lower beam flange. At least two of the vertical frame columns 218a, 218b are rigidly connected to each other by at least one brace member 220, such as a diagonal brace member 222 and / or a horizontal frame beam. Each of the at least two of the vertical frame columns 218a, 218b has an upper end and a lower end, and the lower end is anchored to a concrete foundation using one or more anchor bolts. Various methods commonly known in the art for anchoring the lower end of the vertical frame column to a concrete foundation to provide lateral support to the brace frame against strong seismic events are applicable in the present invention.

[0107] A plurality of brace frames of SFRS may be arranged around the periphery of the grid framework structure (i.e., around each face of the grid framework structure) to form a single frame body, as shown in FIG. 15, i.e., the SFRS forms an exoskeleton that supports the grid framework structure against strong lateral forces as a result of a type C or type D earthquake event. Alternatively, at least one brace frame may be arranged on at least one face of the grid framework structure. The brace frames of the present invention may be arranged on at least one of the four sides of a rectangular parallelepiped. In the particular embodiment shown in FIG. 15, a brace frame is arranged on each of the four sides of the rectangular parallelepiped. The perimeter frame columns 218a at the corners of the grid framework structure are braced by at least one horizontal frame beam 220, 320 extending longitudinally from the top of each of the four perimeter frame columns 218a to form a substantially rectangular or square perimeter frame in the horizontal plane surrounding the perimeter of the grid.

[0108] At least one 218b of the multiple vertical frame columns 218a, 218b may be disposed midway or between two vertical frame columns 218a at the corners of the grid framework structure to divide the exoskeleton into a braced frame where at least two vertical frame columns 218a, 218b are braced by at least one diagonal brace 222 and a drag strut or collector 232. The drag strut or collector 232 is where the at least two vertical frame columns 218a, 218b are braced by a horizontal frame beam 220 at the top of those two vertical frame columns 218a, 218b, and serves to collect and transfer diaphragm shear forces to the vertical frame columns 218a, 218b. In a particular embodiment of the invention shown in FIG. 15, the SFRS comprises a brace frame in which at least two of the plurality of vertical frame columns 218a, 218b are braced by at least one diagonal brace 222 and horizontal frame beam 220 to form a drag strut. Also shown in FIG. 15 is at least one diagonal brace member 222 disposed on one side of the middle vertical support column 218b to form a brace frame 230, and a drag strut 232 disposed on the other side of the brace frame. The bracing between the vertical frame columns at the corners of the SFRS and the middle vertical support column by at least one diagonal brace member on each side of the SFRS around the grid framework structure depends on the nature of the earthquake event, i.e., whether the earthquake event is a type C earthquake event or a type D earthquake event. For a more robust suppression system to respond to a type D earthquake event, a brace frame with at least one diagonal brace according to the present invention is disposed around the perimeter of the grid framework structure. [Modular grid framework structure] In some examples, the seismic grid framework structure 214 may be modularized such that adjacent modules 514 of the grid framework structure in an assembly of two or more modules or modular frames share at least a portion of the SFRS of one or more neighboring modular frames. Each of the modules 514 comprises the seismic grid framework structure described above with reference to FIG. 15, and thus each of the modules 514 comprises a predetermined number of grid cells and a perimeter bracing structure 215 supported by a plurality of vertical frame columns 218a,b of the present invention, which further support the grid. An assembly of two or more modules may be assembled together to increase the storage capacity of the entire seismic grid framework structure, where adjacent modules in the assembly share at least a portion of the perimeter bracing structure of the present invention, i.e., a first modular frame shares at least a portion of the perimeter bracing structure of a second modular frame, whereby the first modular frame is adjacent to the second modular frame. In other words, adjacent modules share a common brace member 220, 222 that is supported by at least two vertical frame columns 218a. The brace members include, but are not limited to, horizontal frame beams 220 and / or diagonal brace members 222.

[0109] Sharing of at least a portion of the SFRS by adjacent modules can be envisaged in the plan view shown in FIG. 22. Four modular grids are shown in FIG. 22 sharing portions of the SFRS of adjacent modular grids. In FIG. 22, a common brace frame 230 of the SFRS, shown as a triangular drawing, is shared between adjacent modular grids 514(a-d). Also, a drag strut 232, shown as a dashed line in FIG. 22, is shared between adjacent modules 514(a-d) such that adjacent modules share the common drag strut 232. Since adjacent modules share at least a portion of the SFRS between adjacent modules, the grids from adjacent modules are connected to the common horizontal frame beam 220, and thus lateral forces generated within the grids of adjacent modules are transferred to the common horizontal frame beam 220. Since the grids are supported at the boundaries of the grids in a manner that portions of the grids overhang the SFRS, the grids from adjacent modules can be coupled to each other by connecting the overhangs from adjacent modules.

[0110] Also shared between adjacent modules are vertical frame columns 218a, 218b that support at least one brace member 220, 222. By sharing portions of the SFRS between adjacent modules, the external brace structures of adjacent modules 514 cooperate together as a single body to deflect lateral forces. In other words, by connecting grids 50 from adjacent modules with common brace members 220, 222, e.g., horizontal frame beams, multiple adjacent grids 50 can function together to form at least one Vierendeel truss, so that lateral forces are transferred across multiple grids to the vertical frame columns 218a, 218b at the perimeter of the module. The perimeter brace structure 215 shared between adjacent modules 514 also provides internal bracing within the assembly of modules 514. The internal bracing includes adjacent modules that share a common brace frame 230 and / or a common drag strut 232.

[0111] The seismic grid framework structure of the present invention allows the mezzanine structure 700 to be integrated with the perimeter brace structure 215 and vertical frame columns 218 of the present invention. The ability to modularize the seismic grid framework structure, described above, allows the mezzanine 702 to share at least a portion of the SFRS of an adjacent module, i.e., to share a common brace frame 230 and / or drag struts 232 with an adjacent or neighboring module. A cross-sectional view of an assembly of modules 514 incorporating a mezzanine 702 integrated within the assembly is shown in FIG. 23. As seen in FIG. 23, the mezzanine structure 700 shares the perimeter brace structure 215 and vertical frame columns 218 of the adjacent module 514, and thus the mezzanine structure 700 is supported by the vertical frame columns 218a,b that support the adjacent module 514. The adjacent module 514 may be a grid framework structure that stores one or more containers or storage bins in a stack. In comparison to the stand-alone mezzanines used in prior art storage systems, the mezzanine of the seismic grid framework structure is integrated within the SFRS such that a separate vertical support column is not required to support the mezzanine.

[0112] To create a mezzanine, the vertical frame columns 218a,b supporting the grid frame structure of adjacent or laterally disposed modules 514 are connected to each other by one or more bracing members, e.g., horizontal frame beams to create a mezzanine floor, and one or more diagonal bracing members 222. The vertical support (frame) columns supporting the mezzanine floor can be braced to provide more support to the mezzanine structure, as shown in FIG. 23. The combination of the SFRS, incorporating the grid framework structure and the mezzanine, provides a single framework that surrounds the assembly. The SFRS is versatile in that the perimeter frame structure 215 is flexible to integrate various other structures into the SFRS, simply by linking the perimeter frame structure and vertical frame columns of adjacent modules together using one or more bracing members, e.g., horizontal frame beams, and thus integrating additional perimeter frame structures to support the grid and / or integrated mezzanines. A plan view of an assembly of modules, each with a seismic grid framework structure on either side of a mezzanine structure 700 to house a station, is shown in Figure 23. As seen in Figure 23, the mezzanine structure 700 is integrated with SFRS on either side of the mezzanine structure 700 such that the SFRS of the individual modules or modular frames 514 are shared to provide an integrated SFRS that encompasses the modules and the mezzanine.

[0113] In the particular arrangement shown in Figure 23, twelve modules 514 are arranged in a 3 x 4 grid. The bold lines indicate the edges of the modules where bracing members (e.g., horizontal frame beams or diagonal bracing members) support the grid 50. The bold lines around the outside of the structure indicate the perimeter frame structure 215. The grid structure 50 extends continuously across the tops of all of the modules 514 so that the load handling device 30 can move across the grid 50 from one module 514 to another.

[0114] The grid framework structure is divided into two parts, and a mezzanine structure 700 extends across a pick aisle 702 between the two parts. The pick aisle 702 can accommodate a pick station or other service area below the grid 50. A perimeter brace structure 215 extends around the modules 514, the pick aisle 702, and the mezzanine 700. An additional mezzanine 704 extends to the side to provide a maintenance area, where load handling devices can be de-inducted from the grid to perform routine maintenance activities or repairs. The mezzanine 704 also provides additional space below the grid 50 for storage or service areas. [Earthquake detection system hardware] 16, an earthquake detection system 300 comprises one or more accelerometers 302 mounted on the grid framework structure 114. The one or more accelerometers 302 may be located at or near the top of the grid framework structure 114. An additional one or more accelerometers 302a may be located on the ground to provide a reference point and allow differential acceleration to be measured at the top of the grid framework structure 114 with respect to the ground. The accelerometers 302 may be located around the periphery of the grid framework structure and / or within the grid framework structure.

[0115] In examples where the grid framework structure 114 comprises an SFRS or perimeter brace structure 215, as is the case in the example shown in Figure 15, the accelerometers 302 may be mounted either on the horizontal grid members 118, 120, or on components of the SFRS, such as on the horizontal brace members 220 or diagonal brace members 222. The accelerometers 302, 302a may be specially designed for the purpose or may be off-the-shelf components.

[0116] As described above with reference to Figures 22 and 23, in examples where the grid framework structure is modular and comprises an assembly of modular frames 514, the accelerometers 302 may be mounted either on the horizontal grid members 118, 120 or on components of the SFRS, for example, on the horizontal brace members 220 or diagonal brace members 222. The accelerometers 302 may be mounted on parts of the SFRS shared between adjacent modules 514, for example, at the intersections of the horizontal brace members or horizontal frame beams 220 at the corners of the modules 514, or in the center of the horizontal frame beams. The earthquake detection system 300 further comprises an input module 304 configured to receive input from the one or more accelerometers 302. In some examples, the input module 304 may also be configured to supply / provide power to the one or more accelerometers 302.

[0117] The earthquake detection system 300 further comprises a controller 306 communicatively coupled to the input module for processing data collected from the one or more accelerometers 302. The controller 306 may be described as a cDAQ (compact data acquisition) and may also be either specially designed for the purpose or an off-the-shelf component. The controller 306 may be provided with a mains power supply.

[0118] The earthquake detection system 300 further comprises an output module 308 coupled to one or more output devices 310. The output module is communicatively coupled to the controller 306 and configured to receive signals from the controller 306 indicative of an earthquake event. The output module 308 may be a relay output module. In some examples, multiple relays may be triggered based on different criteria. The output device 310 may include an alarm, a beacon, a siren, a graphical user interface display, or any other suitable output device. The controller 306 may be located in a maintenance area located adjacent to or near the grid framework structure. The accelerometer 302 may be connected to the controller 306 wirelessly or via a cable (in which case a junction box may be used). Signal processing and data analysis are performed by the controller 306.

[0119] 16 is a simplified schematic diagram of the major hardware components of earthquake detection system 300. As shown, data from accelerometer 302 and ground accelerometer 302a is collected by input module 304 and sent to controller 306. Controller 306 then processes the data and sends signals via output module 308 to output device 310.

[0120] In some examples, the data from the accelerometer (raw data and / or post-processed data from the controller) may be stored in a database, either locally at the maintenance area or in the cloud. In some examples, further processing of the data may occur after the event to confirm that a seismic event occurred and / or to perform further calculations.

[0121] FIG. 21 shows an exemplary embodiment of the controller 306 with its input modules 304 and output modules 308. In this embodiment, the controller is an N9133 cDAQ (Miniature Data Acquisition). A cDAQ chassis 312 houses the controller 306 and provides eight slots into which input or output modules can be inserted. In this example, six of the slots are occupied by input modules 304 (NI-9231) for receiving data from the accelerometer 302, one slot is occupied by an output module 308 (NI-9482 relay output module), and one slot is occupied by a digital input / output module 314 (NI-9401). In this system, the digital input / output module 314 can be used as a digital output to drive an output device 310 and also receive fault alarms from auxiliary equipment. The cDAQ is enclosed in an external casing 316 that also houses other components, as described below.

[0122] The input module 304 is connected to an input terminal 318 which is connected to a connection point 320 on the outside of the outer casing 316. The connection point 320 connects cables from the accelerometer 302 on the grid framework structure and also connects cables from a ground accelerometer 302a located on the ground.

[0123] The output module 308 is connected to a relay output terminal 322, which is connected to an output device 310 (in this case a beacon and a buzzer with three different colors). When an earthquake event is detected, the beacon can light up to provide a visual indication and the buzzer can sound to provide an audible warning. Different colors can be used to represent the severity of the earthquake event (e.g., red for the most severe event, yellow for a less severe event, and green if no event was detected). After an earthquake event, the output device 310 can be reset using an alarm reset key switch 324.

[0124] A UPS (uninterruptible power supply) 326 and a UPS battery 330 are provided that connect to the controller 306 via a power input terminal 328. The UPS ensures that the earthquake detection system can still operate if the main power is interrupted. A UPS is generally used to provide emergency power to a load when there is a failure in the input power or main power, providing near instantaneous protection from input power interruptions.

[0125] A wireless router 332 is provided for transmitting data from the controller. A wireless antenna 334 is provided on the outside of the external casing 316. Data from the controller may be transmitted to a computer and stored locally (e.g., in a maintenance area) or in the cloud, as described above.

[0126] The outer casing 316 is provided with attachment points 336 for attaching the outer casing to a wall or other structure.

[0127] FIG. 17 shows one possible arrangement of the system architecture where post-event data processing takes place in the cloud. In this example, the accelerometers 302 are located on the SFRS beams or brace members 220, 222 of the grid framework structure or on the horizontal members 118, 120. An additional accelerometer 302b is located on the ground. Inputs from all of those accelerometers are directed to a controller 306 by a junction box 312. The controller processes the data from the accelerometers and a visual indicator (one example of an output device 310) indicates whether an earthquake event has been detected. Data from the controller (which may be raw or processed data from the accelerometers) is directed to a wifi router 314 and then sent to a cloud database 316. Further processing of the data may occur in the cloud via a cloud processor 318, and a graphic user interface 320 may use data from the cloud processor obtained via a web app to display visual indicators of failures and / or more detailed data. The advantage of processing data on the cloud is that the data can be viewed from anywhere, on-site or off-site, to monitor the status of the grid framework structure and to further understand the impact of seismic events.

[0128] In some examples, the controller 306 of the earthquake detection system may be integrated into other control systems for the grid framework structure 114 .

[0129] The one or more output devices 310 may be used by personnel to check the status of the grid framework structure and determine whether it is structurally safe to access after an event. Visual and audible indicators may be used to communicate the status and inform personnel whether it is safe to access the grid. For example, the visual indicator may show a red, amber, or green status. A red status means that the grid framework structure is unsafe and the building needs to be evacuated, an amber status means that the grid framework structure is safe for personnel to enter but needs to be inspected and repaired or realigned before load handling devices can operate on the grid, and a green status means that the grid framework structure is safe to continue operating.

[0130] In some cases, a spectral acceleration threshold may be used to determine whether the status is red, amber, or green. For example, if the measured acceleration exceeds a predetermined spectral acceleration threshold, the status of the grid framework structure may be classified as "red." In some cases, there may be more than one predetermined spectral acceleration threshold, for example, if a lower spectral acceleration threshold is exceeded, the status may be defined as "amber" and if an upper spectral acceleration threshold is exceeded, the status may be defined as "red."

[0131] The one or more output devices 310 may be remote, i.e., not located inside the building in which the grid framework structure is stored, so that personnel can check the status remotely if they do not have access to the building.

[0132] After an earthquake event, one or more output devices may be reset (e.g., alarms may be turned off) so that they do not continue to operate after investigation and / or corrective action. [Positioning the accelerometer on the grid] FIG. 18 shows two possible arrangements of accelerometer locations on the grid structure 50. In FIG. 18(a), the majority of the accelerometers 302 are placed in a diagonal across the center of the grid structure 50. In FIG. 18(b), the accelerometers 302 are placed along the perimeter of the grid structure 50 along two of the four edges. In either case, an additional accelerometer 302a is positioned on the ground to measure the differential acceleration of the accelerometers on the grid structure relative to the ground. Of course, these are only illustrative examples and any suitable arrangement of accelerometers 302 on the periphery of the grid structure and / or within the grid structure may be used.

[0133] In instances where the grid framework structure includes SFRS or external braced structures, it may be advantageous to place the accelerometers on the structural members of the braced structures, as these members are expected to buckle first in a seismic event. In the grid framework structure shown in Figure 15, for example, the accelerometers may be placed on the horizontal frame beams 220 or diagonal brace members 222 of the perimeter braced framework.

[0134] The accelerometers 302 may be located at or near the top of the grid framework structure, allowing the displacement of the grid to be measured relative to the displacement on the ground, giving an indication of the deflection at the top of the structure.

[0135] The accelerometer 302a located on the ground may be attached to a concrete foundation or slab on which the grid framework structure is built, or alternatively, the accelerometer 302a may be placed directly on top of the soil (e.g., located inside a hole in the concrete foundation slab).

[0136] A recent study (see https: / / www.nature.com / articles / s41598-018-37716-y) found that the asymmetric vertical acceleration records observed during a magnitude 6.3 earthquake could be explained by the "flapping effect", i.e., local elastic bounce of the foundation slab on which the sensor was placed. The results suggest that the extremely large accelerations recorded did not reflect actual ground shaking, but were caused by local system responses around the sensor. This finding has important implications for both the assessment of earthquake hazards and the installation methodology of accelerometers in all earthquake-prone countries. A simulation model consisting of a foundation slab and an irregular contact surface between the slab and the underlying soil successfully explained both the mainshock and aftershock records. The elastic bounce ("flapping effect") of a slab, e.g. a foundation slab resting on an irregular surface, is induced by a vertical movement through the system, accompanied by a variation in the horizontal direction. Rather than representing the actual shaking of the ground, the measurements are, at least in part, the local system response around the sensor.

[0137] The irregular contact surface allows for localized elastic rebound of the concrete slab during earthquake ground shaking. Such irregular contact surfaces, which may have been created by differential settlement of soil over time or soil erosion, were confirmed by field investigations, where several small gaps (<1 cm) were found between the concrete slab and the soil ground.

[0138] To prevent similar soil-slab interactions in grid framework structures, the foundation slab may be rigidly attached to the soil ground, for example using piles or anchors. Alternatively or additionally, the slab properties (thickness, stiffness) may be designed to minimize the effect of elastic bounce. Alternatively or additionally, the ground accelerometer 302a may be placed directly on the soil ground, for example through a hole or gap in the foundation slab. The term "located on the ground" in this specification should be interpreted to cover both the situation where the accelerometer 302a is fixed to the foundation slab and the situation where the accelerometer is located directly on the soil ground.

[0139] Further examples of possible arrangements of accelerometer locations as applied to the modular seismic grid framework structure previously described and shown in FIG. 23 are shown in FIGS. 24-28.

[0140] In the arrangement shown in FIG. 24, five accelerometers 302 are located on the grid framework structure. As in FIG. 18, an additional accelerometer 302a is positioned on the ground to measure the differential acceleration of the accelerometers on the grid structure relative to the ground. The accelerometers 302 are located at the intersection points of the modules 514. In the example shown, the accelerometers are mounted on brace structures, which may be on vertical frame columns or horizontal frame beams or diagonal brace members. Four of the accelerometers are positioned in a diagonal, with the fifth accelerometer collinear with the fourth accelerometer.

[0141] In the arrangement shown in Figure 25, in addition to the ground accelerometer 302a, nine accelerometers 302 are located on the grid framework structure. Five of the accelerometers are in the same locations as in the example shown in Figure 24. Four additional accelerometers are placed intermediate the five accelerometers of Figure 24, positioned at the center of the module 514 rather than at the intersections. The accelerometers may be mounted on horizontal grid members (track supports). Again, the majority of the accelerometers extend diagonally across the grid.

[0142] In the arrangement shown in Fig. 26, in addition to the ground accelerometer 302a, eight accelerometers 302 are located on the grid framework structure. The accelerometers are arranged along two edges of the grid framework structure. One line of the accelerometers extends in a first direction (X direction) and a second line of the accelerometers extends in a second direction (Y direction). As in the example shown in Fig. 24, the accelerometers 302 are located at the intersection points of the modules 514 and are mounted on the brace structure.

[0143] In the arrangement shown in Fig. 27, in addition to the ground accelerometer 302a, fifteen accelerometers 302 are located on the grid framework structure. Eight of those accelerometers 302 are in the same locations as in Fig. 26. An additional seven accelerometers are positioned intermediate the eight accelerometers of Fig. 26, positioned midway along the edge of the module 514 rather than at an intersection. Again, one line of accelerometers extends in a first direction (X direction) and a second line of accelerometers extends in a second direction (Y direction). As in Fig. 26, the accelerometers are positioned along two sides of the grid framework structure.

[0144] In the arrangement shown in Figure 28, in addition to the ground accelerometer 302a, 28 accelerometers 302 are located on the grid framework structure. The accelerometers are positioned around the perimeter of the perimeter brace structure 215 along all four edges of the brace structure, where two lines of accelerometers extend in a first direction (X direction) and two lines of accelerometers extend in a second direction (Y direction), meeting at the four corners of the grid to form a substantially rectangular shape around the perimeter of the grid.

[0145] These placements of accelerometers are examples only and other placements are possible. The illustrated examples are applied to a modular seismic grid framework structure, however these placements of accelerometers may also be used on standard non-seismic grid framework structures, either modular or non-modular. The number of accelerometers may scale with the size of the grid. In examples where the grid is modular, the number of accelerometers may scale with the number of modules 514.

[0146] In some instances, increasing the number of accelerometers beyond a given number will yield diminishing returns, i.e., further increases in the number of accelerometers will not provide substantial further improvement in the accuracy of the acceleration data. The marginal improvement in accuracy from adding more accelerometers to an earthquake detection system may not justify the increased cost and increased complexity of a system with a larger number of accelerometers.

[0147] The distribution of accelerometers on a grid framework structure is different from the distribution that would be required for other structures, for example for a building. A building may have one or two accelerometers on each floor, but a grid framework structure has a larger number of accelerometers at or towards the top of the grid framework structure. This difference in distribution is required because an earthquake detection system on a grid framework structure can detect which part of the grid is damaged, and a typical grid framework structure for storage and retrieval systems extends over a wide area. On the other hand, an earthquake detection system in a building needs to determine which floor of the building is safe for humans to enter, and therefore the accelerometers may be distributed vertically (one on each floor) rather than horizontally (many accelerometers on the upper floors). In a building, the purpose of the earthquake detection system is to assess the structural integrity of each floor or each level of the building, while in a grid framework structure, the purpose of the earthquake detection system is to assess the structural integrity of the entire grid framework structure, which is located on the ground in the building.

[0148] A typical building in an earthquake zone is a tower block or other tall multi-storey building with many floors, but does not extend over a wide area compared to the height of the building. This is especially true in locations such as Japan, where available land is at a premium and there is therefore a tendency to build upwards rather than outwards. For this reason, the distribution of accelerometers is different from what would be typical in a tall building, with the accelerometers distributed horizontally rather than vertically, at or near the top of a grid framework structure. The accelerometers may be distributed in a substantially horizontal plane.

[0149] For example, FIG. 29 shows a grid framework structure with an accelerometer arrangement as in FIG. 26, where the accelerometers are arranged along two edges of the grid framework structure and are mounted on the horizontal frame beam 220. In particular, the accelerometer labeled 302b is mounted on the horizontal frame beam labeled 220b, and the accelerometer labeled 302c is mounted on the horizontal frame beam labeled 220c. In the illustrated example, only accelerometer 302b and accelerometer 302c measured significant accelerations sufficient to determine that the horizontal frame beams 220b and 220c to which these two accelerometers are attached have deflected and moved away from their initial positions. The other accelerometers 302 measured accelerations that did not indicate deflection. The location of the two accelerometers 302b and 302c allows the most damaged parts of the grid to be identified. The damaged parts of the grid, along with the deflected horizontal frame beams 220b and 220c, are highlighted on Figure 26 with asterisks. This information is useful because it indicates that other parts of the grid (e.g., the upper left corner) are undamaged and may be able to continue to operate and are safe for human entry.

[0150] The use of several accelerometers at different locations distributed over the grid framework structure, rather than a single accelerometer, is advantageous because it allows the damaged section(s) of the grid to be identified after a seismic event. The placement of accelerometers around the grid on two or more edges is particularly useful because they allow identification of which parts of the grid are sufficiently intact to continue operating normally, which parts are too damaged to immediately resume operation but are safe enough to bring in personnel to repair the damage, and which parts are dangerous to personnel.

[0151] In examples where the grid framework structure is a seismic grid framework structure (either a modular structure or a single structure), the accelerometers may be mounted directly on the brace structures. In particular, the accelerometers may be mounted on the horizontal frame beams 220 that extend horizontally along the edges of the grid. If the accelerometers mounted on the horizontal frame beams indicate residual drift, the horizontal frame beams are deflecting. Positioning the accelerometers on the perimeter brace structures 215 allows the earthquake detection system to determine whether members of the perimeter brace structures are deflecting. In examples where the grid framework structure is an assembly of modular frames (as in FIG. 23), determining which members of the perimeter brace structures are deflecting may allow individual modules 514 to be categorized into different states or failure modes depending on the amount of residual drift. [Failure mode] A seismic event may result in a variety of different failure modes or conditions of the grid framework structure that have different consequences and require different actions. Elastic limit - the moment prior to deflection of the bracing members. If the bracing members are still within their elastic limits, there is no permanent deformation of the grid framework structure and normal operation can continue after a seismic event. The elastic limit state occurs below an acceleration of approximately 0.6g. Immediate occupancy - The level of tolerable plastic or elastic deformation that allows personnel to safely re-enter a building after a seismic event to assess and repair damage. The immediate occupancy condition occurs for accelerations between about 0.6g and about 1g. Life Safe - The grid framework structure may have significant structural damage but has reserve structural capacity to withstand aftershocks. The building may not be able to be used until after repairs have been made. Life safe conditions occur for accelerations between about 1g and about 1.83g. Collapse Prevention - The grid framework structure has been pushed to the limits of its strength and stiffness and is on the verge of collapse. Aftershocks may cause the grid framework structure or the building to collapse. The collapse prevention condition occurs for accelerations above about 1.83g.

[0152] The condition of the grid framework structure may also be determined based on the spectral accelerations measured by the accelerometers on top of the grid framework structure. The grid framework structure has a natural period and a natural frequency that will depend on the size, shape, and material from which the grid framework structure is constructed. After a seismic event occurs, the data may be analyzed to determine if the frequency spectrum during the seismic event contained components that were close to the natural frequency of the grid framework structure, and if so, further damage would be expected since applied vibrations close to the natural frequency or natural period would result in resonance and therefore higher amplitude of vibration.

[0153] Many building codes impose limits on the maximum movement permitted during a seismic event before a structure is classified as "deficient." For example, in the United States, the maximum allowable lateral displacement measured during a seismic event is 2% of the height of the structure, and in Japan, the maximum allowable lateral displacement measured during a seismic event is 0.5% of the height of the structure. If a structure is classified as "deficient" according to a building code, the structure may need to be recertified by an appropriately qualified person before it can be considered to comply with the building code.

[0154] A grid framework structure can be a very large structure with thousands of components that can potentially fail. Without a means to identify where the damage occurred, every critical part of the grid framework structure would have to be inspected individually. While visual inspection of parts on the outside of the grid framework structure is relatively straightforward, inspecting the interior parts of the grid framework structure would be very time consuming, especially given the presence of a stack of storage containers, which would need to be moved to allow visual inspection of the components within the grid framework structure.

[0155] When a storage and retrieval system is taken offline for inspection after a seismic event, this is extremely costly since the system cannot fulfill customer orders while it is offline. It is therefore advantageous to minimize downtime and get the storage and retrieval system up and running as quickly as possible.

[0156] On the other hand, if the storage and retrieval system continued to operate when it was damaged, this could affect or jeopardize other systems, and therefore it is important to ensure that the system is safe and capable of normal operation before bringing it back online.

[0157] There is a large difference in cost between a "ready for use" failure mode and a "life safety" failure mode. If there is no way to distinguish what state the grid framework structure is in, a more cautious approach must be taken to avoid endangering life.

[0158] In some instances, particularly where the grid framework structure is modular, different parts of the grid framework structure may be in different states, for example some parts may be safe to continue operating normally, some parts may be safely entered by personnel to replace damaged parts, and some parts may be unsafe. Understanding the state or failure modes of the different parts of the grid framework structure allows downtime to be minimized while ensuring personnel safety and compliance with building codes. [Method for generating displacement data] A method for generating displacement data to determine if a seismic event has occurred is shown in FIG. 19 and described below.

[0159] In step 101, raw data is captured by an accelerometer in the form of an acceleration versus time signal.

[0160] The data is filtered in step 102. The controller's first task upon receiving the signal from the accelerometer is to filter the signal to remove excessive noise. This may be done, for example, by using a bandpass filter to band limit the waveform (i.e., to attenuate or remove vibrations above or below a specified frequency band), or by using a high-pass filter to attenuate low frequency vibrations, or a low-pass filter to attenuate high frequency noise.

[0161] Additionally, the controller may filter out other known sources of noise, such as vibrations caused by load handling devices moving on the grid framework structure, or frequencies associated with other components or peripherals on the grid framework structure, or even in the same building. To do this, known sources of noise may be characterized by recording a background acceleration signal in the absence of seismic activity, and then analyzing this background acceleration signal to determine characteristic background frequencies, for example, by calculating a Fourier transform of the collected signal in the frequency domain. These characteristic background frequencies may then be filtered out or attenuated from the acceleration signal received by the controller from the accelerometer. Alternatively, the Fourier transform of the background acceleration signal may be subtracted from the Fourier transform of the acceleration signal from the accelerometer, thus removing events with characteristic background frequencies from the signal. In this way, detecting seismic events becomes easier, as anomalous events may be more easily distinguished from background noise.

[0162] Filtering out known sources of noise is important for earthquake detection systems for grid framework structures, especially those that do not have an exoskeleton to provide additional support during earthquake events. Acceleration and deceleration of load handling devices as they move on top of the grid is an additional movement that must be taken into account. This movement will affect accelerometer readings much more than, for example, people moving in a building, because people in a building may not all be at the top of the structure but may be vertically distributed on different floors, may be moving slower, and may not be moving continuously. People in a building may move vertically at least as much as horizontally (e.g., riding elevators, going up and down between different floors), and a building may be empty at a given time rather than full of people moving continuously. For this reason, filtering out known sources of noise is advantageous.

[0163] A ground accelerometer 302a is provided that is located on the ground, beside or below the grid framework structure. The ground accelerometer measures acceleration at ground level. In step 103, the acceleration at ground level is then used to calculate a differential acceleration of the accelerometer at the top of the grid framework structure relative to the ground. The controller subtracts the acceleration signal measured by the ground accelerometer from the acceleration signal measured by the accelerometer at the top of the grid framework structure to calculate the differential acceleration.

[0164] In step 104, the controller determines the displacement of the grid framework structure relative to the ground from the calculated differential acceleration. This may be accomplished mathematically by performing a double integration on the differential acceleration signal (i.e., integrating once with respect to time to obtain a velocity signal, and then integrating again with respect to time to obtain a displacement signal). Thus, a displacement signal is obtained from each of the accelerometers.

[0165] In step 105, the displacement data may be analyzed to determine whether a seismic event has occurred. [Detecting earthquake events from displacement data] Figure 20 shows an example of displacement data calculated from accelerometers on a grid framework structure during a seismic event. Displacement is plotted as a function of time. There are three distinct regions of displacement response that can be seen on the graph: non-proportional response, period elongation, and residual drift.

[0166] The first region is a non-proportional response, characterized by high amplitude spikes. In this region, the amplitude (displacement response) is not proportional to the applied force. This indicates that the flexural strength of the structural member has been exceeded and the material no longer exhibits linear elastic behavior. In the absence of a seismic event, the material of the structural components behaves linearly and follows Hooke's Law, where the displacement is proportional to the applied force.

[0167] F=kx where F is the applied force, k is the stiffness or spring constant of the material, and x is the displacement. The stiffness k depends on the cross-sectional area, length, and Young's modulus of the material. The above formula is true when the material of a structural component is below its flexure strength. When the flexure strength is exceeded, the material begins to behave nonlinearly and the value of k is no longer a constant. In the non-proportional response region, the displacement can be higher than would be expected when the material is behaving elastically.

[0168] The non-proportional response may be detected by determining whether the amplitude of the displacement signal exceeds a predetermined displacement threshold corresponding to the elastic limit of a structural member of the grid framework structure. Alternatively, the non-proportional response may be detected by comparing the acceleration signal (after filtering) to the displacement signal and determining whether the amplitudes of the two signals are proportional.

[0169] The second region is periodic elongation, where the time period of vibration is increased from its normal value. This occurs because the deflection changes the dynamic properties of the grid framework structure. To determine the period of vibration, a Fourier transform of the signal in the frequency domain can be calculated. The largest spike in the frequency domain will be the vibration frequency of the grid framework structure during the periodic elongation region of the seismic event. To determine if the period has changed, the vibration period can be compared to a reference period, which corresponds to the natural frequency of the vibration of the grid framework structure. The natural frequency can be determined by taking a Fourier transform of the displacement signal in the absence of a seismic event.

[0170] The third region is residual drift, where there is a static non-zero displacement that remains after the displacement vibrations have stopped or returned to their normal levels. This can be seen as the dashed line on Figure 20, where the displacement has shifted away from zero after the amplitude of the vibrations has reduced. This residual drift or residual displacement is an indication of how far the accelerometer has moved from its original position, i.e., how far the structural member to which the accelerometer is attached has moved.

[0171] These three areas (nonlinear response, period stretching, residual drift) provide three different methods to identify faults from the displacement time signal. In practice, any one of these three methods may be used, or a combination of two or all three may be used. The simplest method is residual drift, since it simply means that the structure has moved after the earthquake event, which suggests a fault. It has the advantage that it is easy to estimate the degree of structural deflection from the magnitude of static displacement. However, the residual drift method alone may not be accurate enough and is prone to the risk of false positives (for example, if the accelerometer moves and not the grid structure itself). Using a combination of methods will give more accurate results.

[0172] The non-proportional response method and the cyclic elongation method are more complicated and require more analysis. However, these two methods are more indicative of deflection failure in the grid framework structure because the only time the non-proportional response and cyclic elongation phenomena occur is when the grid framework structure is deflected. If a non-proportional response and / or cyclic elongation is detected, there may be a deflection failure. It is more difficult with these methods to determine the degree of deflection failure, but the residual drift allows for an easy estimation of the degree of deflection. Therefore, it is preferable to use a combination of all three methods. [Adaptive gain control and offset compensation] In some cases, adaptive gain control may be used to compensate for the difference between the predicted and measured peak-to-peak displacements as a function of frequency, as described below. For a range of frequencies, the peak-to-peak displacement of the accelerometer is calculated according to the method described above and shown in FIG. 19. The calculated peak-to-peak displacement is compared to the measured peak-to-peak displacement. At low frequencies, the calculated peak-to-peak displacement tends to underestimate the displacement. Filtering out the low frequencies from the acceleration signal by using a high-pass or bandpass filter makes the calculated displacement more accurate (closer to the measured displacement).

[0173] If the error in the displacement calculation is a fixed percentage of the displacement, the error can be corrected by multiplying the calculated displacement by a gain or scale factor. This procedure is repeated over a range of frequencies, which produces a reference curve of gain or scale factor versus frequency. This reference curve can be applied to the calculated peak-to-peak displacement to correct for the error and more accurately estimate the peak-to-peak displacement of the accelerometer.

[0174] To simulate residual drift (see residual drift region shown in FIG. 20), an acceleration signal is created by superimposing peak-to-peak vibration and static displacement to simulate deflection of structural elements within the grid framework structure. The acceleration signal is filtered and integrated twice to calculate a displacement signal. The calculated displacement signal exhibits an initial transient response that may be expected as a result of double integration, after which the signal settles to its expected position (i.e., static displacement).

[0175] Accelerometers do not measure exactly zero when stationary due to background noise and due to an instrument input offset voltage in the acceleration measurement. This offset voltage is small, but increases when double integrated over a long period of time. To compensate for this effect, offset compensation (e.g., by an averaging algorithm) is applied to the signal to cancel the offset voltage. As with dynamic displacement, the calculated static displacement tends to be underestimated at low frequencies, therefore adaptive gain control may be applied as described above for peak-to-peak displacement calculation. [Multi-storey storage system] The earthquake detection system and method of the present invention can be equally applied to a multi-storey storage system located in a multi-storey building. In some examples, as well as having a grid framework structure on the ground floor of a building, an additional grid framework structure can be located on one or more upper floors of the building. For example, a perimeter grid framework structure for warm goods can be located on the ground floor, and a (usually smaller) cooling grid framework structure for cold goods can be located on the upper floor. This can be the second floor of the building, i.e., the floor immediately above the ground floor, or a higher floor, for example, the third floor or the fourth floor or the fifth floor. In other examples, there can be three or more grid framework structures located on different floors in the same building. In some examples, a single grid framework structure can be located on a higher floor of a multi-storey building, rather than on the ground floor.

[0176] Figure 30(a) shows an example with a single storey building 100 with a single grid framework structure 101 located on the ground floor 102 of the building 100. As in the previous example, one or more ground accelerometers 105 are located on the ground (either on the substructure supporting the lower grid framework structure 101 or just above the soil ground, as previously explained). One or more accelerometers 106 are mounted on the grid framework structure 101, i.e., either on the grid or on the supporting framework structure.

[0177] FIG. 30(b) shows an example with a multi-storey building 100 having a lower grid framework structure 101 located on the ground floor 102 of the building 100 and an upper grid framework structure 103 located on an upper floor 104 of the building 100. The upper floor 104 can be the second floor of the building 100, as in the illustrated example, or another upper floor. As in the previous example, one or more ground accelerometers 105 are located on the ground (either on the substructure supporting the lower grid framework structure 101, as previously explained, or just above the soil ground). One or more accelerometers (which will be referred to as lower grid accelerometers 106) are mounted on the lower grid framework structure, i.e., either on the grid or on the supporting framework structure. On the upper floor 104, one or more accelerometers 107 (which will be referred to as upper floor accelerometers 107) are located on the floor at the bottom of the upper grid framework structure 103. One or more accelerometers 108 (which will be referred to as upper grid accelerometers 108) are mounted on the upper grid framework structure 103, either on the grid or on the supporting framework structure.

[0178] Seismic demand is the acceleration or force that ground movement (represented by the signal shown in FIG. 30) imparts to a building or structure. The seismic demand at the ground will be measured by the ground accelerometer 105. The seismic demand on the upper floors will depend on both the ground acceleration and the building movement. Generally, the seismic demand will be higher on the higher floors of the building. The seismic demand in FIG. 30 is represented by the right-pointing arrow. In FIG. 30(b), the right-pointing arrow on the upper floor 104 is longer than that of the ground floor 102, representing a higher seismic demand (and higher acceleration / displacement) of the upper floor 104 and therefore the upper grid framework structure 103.

[0179] Seismic capacity is the acceleration or force that a building or structure can withstand, which is a function of the material and design of the structure. In engineering design, it is a requirement that the seismic capacity be greater than or equal to the earthquake demand. The seismic capacity of the upper grid framework structure and the lower grid framework structure is indicated by the left-pointing arrow in Figure 30 and is the same regardless of which floor the grid framework structure is located on.

[0180] When calculating the differential acceleration for the grid framework structure on the upper floor, the same method may be used as described previously in this application. The differential acceleration may be calculated by taking the difference between the acceleration measured by the upper grid accelerometer 108 and the acceleration measured by the upper floor accelerometer 107, as well as by taking the difference between the acceleration measured by the upper grid accelerometer 108 and the acceleration measured by the ground accelerometer 105. This allows the movement of the upper grid structure 103 to be characterized both relative to the floor it rests on within the building 100, and relative to the ground. [Seismic isolation] In some examples, the grid framework structure includes an earthquake isolation system for reducing seismic forces acting on the grid framework structure. A cross-sectional view of an example of an earthquake isolation system 208 is shown in FIG. 31. The earthquake isolation system 208 includes a superstructure or diaphragm 202 and a substructure or foundation 200. The superstructure 202 includes at least a portion, and in some cases, all, of the load-bearing structure of the grid framework structure 114. The superstructure 202 may be a concrete load-bearing structure. The grid framework structure 114, and more particularly the footings of the upright columns 116, are attached to the superstructure 202 by one or more anchor bolts. The upright columns 116, and thus the grid framework structure 114, are attached to the superstructure 202 by one or more adjustable feet 90 and / or anchor feet 132. Further details of the adjustable feet and anchor feet have been described above. The requirement of a superstructure 202 at the bottom of the grid framework structure has the benefit of redistributing the aggregated forces from one or more individual brace frame locations to a relatively larger number of support points. The substructure 200 comprises at least the foundation of the grid framework structure, which may be the ground or a concrete foundation.

[0181] Intermediately disposed between the superstructure 202 and the substructure 200 are one or more isolation devices 204. The distribution of the isolation devices 204 can be adjusted to eliminate irregularities or possible twisting issues in the superstructure 202. The isolation devices 204 isolate the superstructure 202, and thus the grid framework structure 114 mounted thereon, from substructure or ground movements during an earthquake. In this way, large deflections and high accelerations are prevented from being transmitted to the grid framework structure 114. The number and distribution of the isolation devices 204 depend on the weight of the grid framework structure, the height of the grid framework structure, and the composition of the ground. For example, the energy of seismic waves with higher frequencies tends to be absorbed by hard rock soils, while seismic waves with lower frequencies pass through hard rock soils without being absorbed, but are ultimately amplified by soft sediments. The isolation devices may be distributed in an array having a grid-like pattern, with each of the isolation devices 204 attached between the substructure 200 and the superstructure 202 by a lower mounting plate and an upper mounting plate, respectively. The isolation devices provide lateral flexibility for the seismic isolation system to damp ground movements transmitted to the grid framework structure. Various known isolation devices that attempt to obtain maximum energy dissipation through seismic control are permissible in the present invention. Options include (but are not limited to) elastomeric bearings, sliding bearings, or combinations thereof.

[0182] In instances where the grid framework structure is located in a multi-storey building, the grid framework structure may be located on an upper floor rather than on the ground floor. Alternatively, in addition to the grid framework structure located on the ground floor, a second grid framework structure may be located on the upper floor. Typically, earthquake demands in a multi-storey building are higher for the upper floors, but in instances where the entire building utilizes an earthquake isolation system (i.e., the building is supported by a superstructure 202 that can move relative to the substructure 200), in some cases the earthquake demands may be lower on the higher floors than on the ground floor. [Definition] As used herein, the phrase "movement in the n-direction," where n is one of x, y, and z, (and related expressions) is intended to mean movement in either direction substantially along or parallel to the n-axis (i.e., toward the positive end of the n-axis or toward the negative end of the n-axis). As used herein, the word "connect" and its derivatives are intended to include the possibilities of direct and indirect connections. For example, "x is connected to y" is intended to include the possibilities of x being directly connected to y, without any intervening components, and the possibilities of x being indirectly connected to y, with one or more intervening components. Where a direct connection is intended, the words "directly connected," "directly connected," or the like, will be used. Similarly, the word "support," and its derivatives are intended to include the possibilities of direct and indirect contact.

[0183] For example, "x supports y" is intended to include the possibility that x directly supports and directly contacts y, without any intervening components, and the possibility that x indirectly supports y, with one or more intervening components contacting x and / or y. The word "mount" and its derivatives are intended to include the possibilities of direct and indirect mounting. For example, "x is mounted on y" is intended to include the possibility that x is directly mounted on y, without any intervening components, and the possibility that x is indirectly mounted on y, with one or more intervening components.

[0184] As used herein, the word "comprises" and its derivatives are intended to have an inclusive rather than exclusive meaning. For example, "x comprises y" is intended to include the possibilities that x contains one and only y, contains multiple y, or contains one or more y, and contains one or more other elements. When an exclusive meaning is intended, the phrase "x consists of y" is used, which means that x contains only y and nothing else.

Claims

1. 1. A method for detecting an earthquake event, the method comprising: a) collecting acceleration data over a given period of time from one or more accelerometers 302 located on a grid framework structure 114, wherein said grid framework structure 114 comprises: i) a first set of horizontal grid members 118 extending in a first direction; ii) a second set of horizontal grid members 120 extending in a second direction substantially perpendicular to the first direction and intersecting the first set of horizontal grid members 118 at an intersection 56, wherein the first set of horizontal grid members 118 and the second set of horizontal grid members 120 are arranged to form a grid 50 comprising a plurality of substantially rectangular frames 54 in a horizontal plane, each of the substantially rectangular frames defining a grid cell; iii) a plurality of upright columns 116 supporting the first set of horizontal grid members 118 and the second set of horizontal grid members 120, wherein the plurality of upright columns 116 form a plurality of vertical storage locations for containers 10 to be stacked between the upright columns 116; Equipped with b) comparing the collected acceleration data with ground acceleration data from one or more accelerometers 302a located on the ground; c) determining a differential acceleration between said acceleration data and said ground acceleration data; d) determining displacement data from said differential acceleration; e) determining whether a seismic event has occurred over the given time period based on the displacement data; A method comprising:

2. 2. The method of claim 1 , wherein the step of determining whether a seismic event has occurred over the given period of time comprises determining whether the displacement data exceeds a predetermined displacement threshold corresponding to an elastic limit of members of the grid framework structure 114.

3. 3. The method of claim 1 or 2, wherein the step of determining whether a seismic event has occurred comprises determining a change in frequency and / or period of vibration of the displacement data over the given period of time.

4. 4. The method of claim 3, wherein determining a change in the frequency and / or period of vibration of the displacement data comprises determining whether the frequency and / or period of vibration differs from a predetermined frequency threshold and / or a predetermined period of vibration.

5. 5. The method of claim 1, wherein the step of determining whether a seismic event has occurred over the given period of time comprises determining a static displacement from the displacement data and determining whether the static displacement exceeds a predetermined static displacement threshold.

6. 6. The method of claim 1, further comprising filtering the acceleration data to remove or attenuate one or more signals associated with non-seismic events.

7. The method of claim 6 , wherein the step of filtering the acceleration data comprises using a high pass filter, a low pass filter, and / or a band pass filter.

8. 8. The method of claim 6 or 7, wherein the step of filtering the acceleration data to remove or attenuate one or more signals associated with non-seismic events comprises determining frequency ranges in which vibrations occurred in the absence of a seismic event and attenuating or filtering out these frequency ranges from the acceleration data.

9. 9. The method of claim 1, wherein the one or more accelerometers 302 located on the grid framework structure 114 comprise a plurality of accelerometers 302, and the step of determining whether an earthquake event has occurred is based on displacement data from each of the plurality of accelerometers 302.

10. 10. The method of claim 1, further comprising the step of sending a signal to one or more output devices 310 in response to determining that a seismic event has occurred over the given period of time.

11. 1. A method for condition monitoring of a grid framework structure 114 following a seismic event, the grid framework structure 114 comprising: i) a first set of horizontal grid members 118 extending in a first direction; ii) a second set of horizontal grid members 120 extending in a second direction substantially perpendicular to the first direction and intersecting the first set of horizontal grid members 118 at an intersection 56, wherein the first set of horizontal grid members 118 and the second set of horizontal grid members 120 are arranged to form a grid 50 comprising a plurality of substantially rectangular frames 54 in a horizontal plane, each of the substantially rectangular frames defining a grid cell; iii) a plurality of upright columns 116 supporting the first set of horizontal grid members 118 and the second set of horizontal grid members 120, wherein the plurality of upright columns 116 form a plurality of vertical storage locations for containers 10 to be stacked between the upright columns 116; iv) one or more accelerometers 302 located on said grid framework structure 114; Equipped with The method comprises: a) collecting acceleration data from the one or more accelerometers 302 over a given period of time; b) comparing the collected acceleration data with ground acceleration data over the given time period from one or more accelerometers 302a located on the ground surface; c) determining a differential acceleration between said acceleration data and said ground acceleration data; d) determining the extent of damage to different portions of the grid framework structure that occurred during said given time period by determining whether said differential acceleration data exceeds a predefined acceleration threshold during said given time period; A method comprising:

12. 12. The method of claim 11, wherein the predetermined acceleration threshold comprises a plurality of predetermined acceleration thresholds, each of the plurality of predetermined acceleration thresholds indicative of a different level of damage to one or more of the different portions of the grid framework structure.

13. 13. The method of claim 12, wherein the plurality of predetermined acceleration thresholds includes a first acceleration threshold indicative of an elastic limit of a portion of the grid framework structure, such that the differential acceleration of the portion of the grid framework structure that exceeds the first acceleration threshold provides an indication that the portion of the grid framework structure has been permanently deformed.

14. 14. The method of claim 13, wherein the first acceleration threshold is substantially 0.6 g.

15. 15. The method of claim 13 or 14, wherein the plurality of predetermined acceleration thresholds includes a second acceleration threshold indicative of a safety limit, such that the differential acceleration of the portion of the grid framework structure exceeding the second acceleration threshold provides an indication that it is unsafe for personnel to enter the portion of the grid framework structure.

16. 16. The method of claim 15, wherein the second acceleration threshold is substantially 1.0 g.

17. 17. The method of any one of claims 13 to 16, wherein the plurality of predetermined acceleration thresholds includes a third acceleration threshold indicative of a structural limit, such that the differential acceleration of a portion of the grid framework structure that exceeds the third acceleration threshold provides an indication that the portion of the grid framework structure does not have sufficient structural capacity to withstand an aftershock.

18. 20. The method of claim 17, wherein the third acceleration threshold is approximately 1.83 g's.

19. e) determining displacement data from said differential acceleration; f) determining the extent of damage to different parts of the grid framework structure by determining whether the displacement data exceeds a predefined displacement threshold; 19. The method of any one of claims 11 to 18, further comprising:

20. 20. The method of claim 19, wherein the predetermined displacement threshold indicates an elastic limit, such that a displacement of a portion of the grid framework structure beyond the predetermined displacement threshold provides an indication that the portion of the grid framework structure has been permanently deformed.

21. 21. An earthquake detection system 300 for a grid framework structure 114 configured to perform the method of any one of claims 1 to 20, said earthquake detection system 300 comprising: a) one or more accelerometers 302 mounted on the grid framework structure 114; b) an input module 304 configured to collect acceleration data from the one or more accelerometers 302; c) a controller 306 in communication with said input module 304, said controller 306 comprising one or more processors and a memory storing instructions that, when executed by said one or more processors, cause said one or more processors to: i) determining whether a seismic event has occurred based on the collected acceleration data from the one or more accelerometers 302; ii) in response to determining that a seismic event has occurred, sending a signal to one or more output devices 310; To carry out An earthquake detection system 300 comprising:

22. The earthquake detection system of claim 21 further comprising one or more accelerometers 302a located on the ground near the grid framework structure 114.

23. 23. The earthquake detection system of claim 21 or 22, wherein the one or more output devices 310 comprise a beacon, an alarm, and / or a siren.

24. i) a first set of horizontal grid members 118 extending in a first direction; ii) a second set of horizontal grid members 120 extending in a second direction substantially perpendicular to the first direction and intersecting the first set of horizontal grid members 118 at intersections 56, the first set of horizontal grid members 118 and the second set of horizontal grid members 120 being arranged to form a grid 50 comprising a plurality of substantially rectangular frames 56 in a substantially horizontal plane, each of the substantially rectangular frames defining a grid cell 56; iii) a plurality of upright columns 116 supporting the first set of horizontal grid members 118 and the second set of horizontal grid members 120, wherein the plurality of upright columns 116 form a plurality of vertical storage locations for containers 10 to be stacked between the upright columns 116; A grid framework structure 114 comprising:

24. A grid framework structure 114, said grid framework structure 114 further comprising an earthquake detection system 300 according to any one of claims 21 to 23.

25. The grid framework structure 114 of claim 24, wherein the one or more accelerometers 302 mounted on the grid framework structure 114 comprise a plurality of accelerometers 302, the plurality of accelerometers 302 being arranged along the first direction and / or the second direction of the grid 50.

26. The grid framework structure (114) of claim 25, wherein the plurality of accelerometers (302) are positioned along at least a portion of a perimeter of the grid (50).

27. 25. The grid framework structure 114 of claim 24, wherein the one or more accelerometers mounted on the grid framework structure 114 comprise a plurality of accelerometers 302, at least a portion of the plurality of accelerometers 302 being disposed diagonally relative to the first direction and the second direction of the grid 50.

28. 28. The grid framework structure 114 of any one of claims 25 to 27, wherein the plurality of accelerometers 302 lie in a substantially horizontal plane.

29. 29. The grid framework structure 114 of any one of claims 25 to 28, wherein the plurality of accelerometers 302 consists of between 15 and 28 accelerometers 302.

30. The grid framework structure (114) of claim 24, wherein the one or more accelerometers mounted on the grid framework structure (114) are mounted on the horizontal grid members (118,120).

31. 31. The grid framework structure 114 of any one of claims 24 to 30, further comprising an exoskeleton comprising a plurality of vertical frame columns 218 braced by one or more bracing members 220, 222, said grid 50 being further supported by said exoskeleton to form a seismic force suppression system (SFRS).

32. The grid framework structure of claim 31 , wherein the one or more accelerometers mounted on the grid framework structure are mounted on the SFRS.

33. The grid framework structure (114) of claim 32, wherein the one or more accelerometers (302) mounted on the grid framework structure (114) are attached to the one or more brace members (220, 222).

34. 34. A grid framework structure (114) according to any one of claims 24 to 33, wherein the grid framework structure (114) is subdivided into a plurality of modular frames (514) such that the grid (50) extends across the plurality of modular frames (514).

35. 35. The grid framework structure 114 of any one of claims 24 to 34, further comprising an earthquake isolation system 208 for reducing seismic forces acting on the grid framework structure 114, the grid framework structure 114 being supported by the earthquake isolation system 208, the earthquake isolation system 208 comprising an upper structure 202, a substructure 200 and at least one seismic isolation device 204 disposed between the upper structure 202 and the substructure 200, such that the at least one seismic isolation device 204 inhibits movement of the upper structure 202 relative to the substructure 200 in an earthquake event.

36. i) a first grid framework structure at a first level; ii) a second grid framework structure at a second level, said second level being above said first level; A multi-storey grid framework structure comprising:

36. A multi-storey grid framework structure, wherein each of the first grid framework structure and the second grid framework structure comprises a grid framework structure as defined in any of claims 24 to 35.

37. a) a grid framework structure 114 as defined in any one of claims 24 to 36; b) one or more load handling devices 30 remotely operable to move one or more containers 10 stored in said grid framework structure 114, wherein each of said one or more load handling devices 30: i) a wheel assembly for guiding the load handling device 30 on the grid framework structure 114; ii) a container receiving space 40 located above said grid framework structure 114; and iii) a lifting device arranged to lift a single container 10 from the stack 12 and into said container receiving space 40; A storage and retrieval system comprising:

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